Time, Ritual, and Bayesian Reasoning: Charting the Andean Kotosh Religious Tradition

Time, Ritual, and Bayesian Reasoning: Charting the Andean Kotosh Religious Tradition | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Time, Ritual, and Bayesian Reasoning: Charting the Andean Kotosh Religious Tradition Christian Mesía-Montenegro This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6896121/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 Dec, 2025 Read the published version in Archaeological and Anthropological Sciences → Version 1 posted 7 You are reading this latest preprint version Abstract Bayesian chronological modelling offers new leverage for reassessing the tempo and trajectory of early Andean ritual systems. Here I re-evaluate 168 radiocarbon determinations from 16 Late Archaic and Formative sites associated with the Kotosh Religious Tradition (KRT) using an OxCal workflow that combines rigorous sample vetting, outlier modelling, and Monte Carlo–derived Kernel Density Estimation. The resulting high-precision sequences reveal that KRT ceremonial architecture arose virtually simultaneously on Peru’s central coast and in the adjacent highlands by ~ 3600 cal BCE, refuting long-standing diffusionist scenarios that posit a unidirectional spread from one heartland to another. Six statistically robust ritual phases are defined, each bracketed by ≥ 95% highest-posterior-density intervals. Probability distributions for phase boundaries and inter-regional offsets indicate recurrent, multidirectional exchange rather than linear succession. This pattern implies a distributed network of communities negotiating a shared but diversely expressed ritual repertoire, rather than a single center exporting an ideological package. Beyond clarifying KRT chronology, the study demonstrates how transparent “chronological hygiene” protocols paired with Bayesian phase-break analysis can resolve fine-grained cultural dynamics in other early complex societies. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction The Kotosh Religious Tradition (KRT) represents a pivotal ritual phenomenon in the Central Andes during the Late Archaic to Formative periods. Characterized by ceremonial structures featuring central hearths, ventilated chambers, and plastered walls, this tradition played a fundamental role in the development of socio-religious complexity across the region. Despite decades of research, significant debates persist regarding its chronological development and cultural dynamics (Elizabeth Bonnier, 1983 ; Elisabeth Bonnier, 1988 ; Elizabeth Bonnier, 1997 ; R. L. Burger & Salazar-Burger, 1986 ; Mesia-Montenegro & Sanchez-Borjas, 2023 ). Current scholarship presents conflicting interpretations of the KRT's origins, with some researchers advocating for independent development in the highlands at sites like Kotosh and Huaricoto (R. Burger & Salazar, 1985 ; R. L. Burger & Salazar-Burger, 1986 ), while others propose unidirectional diffusion from coastal centers such as Huaricanga or Caral (Creamer, Ruiz, Perales, & Haas, 2013 ; Piscitelli, 2014 , 2017a , 2017b ). These contrasting perspectives stem from persistent challenges in the archaeological record. Ambiguities in temporal overlap between coastal and highland ritual practices, biases in site representation due to stratigraphic gaps and uneven sampling, and the absence of high-precision chronological frameworks have hindered evaluations of cultural hybridity, bidirectional exchange, or ideological movement. These limitations have prevented consensus on the KRT's spatial and temporal trajectory and its role in pan-Andean ideological networks. To resolve these inconsistencies, this study addresses three fundamental questions: First, what were the chronological origins and dissemination pathways of the KRT? Second, how did temporal overlaps between early coastal monumental complexes and highland ritual practices inform patterns of cultural coexistence or ideological change? Third, can we identify evidence for multidirectional cultural transmission that challenges linear diffusion theories? I address these questions through Bayesian chronological analysis of 168 radiocarbon dates from 16 Late Archaic and Formative period sites across Peru's central coast and highlands. This approach aims to establish a unified high-precision timeline that clarifies the KRT's developmental trajectory while providing a framework to assess environmental, political, and religious drivers of social change in early Andean societies. The Late Archaic and Formative Periods The Late Archaic (ca. 3500–1800 cal BCE) in the Central Andes witnessed a dramatic escalation of socio-political complexity that preceded the technological hallmarks traditionally used to mark the ensuing Formative. Coastal centers such as Caral and Huaricanga erected extensive platform mounds, circular sunken plazas, and terraced pyramids in the complete absence of ceramics or loom-woven textiles, overturning the premise that sophisticated craft production is a prerequisite for monumentality (Hass & Creamer, 2006 ; Ruth Shady, 2006 ). These initiatives were sustained by a diversified economy that braided maritime exploitation, floodplain agriculture, and highland foraging, fostering population growth and long-distance exchange (Pozorski & Pozorski, 1990 ). While coastal sites invested in large, communal architectural programs that anchored emerging elites, highland settlements such as Huaricoto and Piruru expressed the same ideological repertoire through more modest, hearth-centered shrines linked to the Kotosh Religious Tradition (Elizabeth Bonnier, 1997 ; R. L. Burger & Salazar-Burger, 1986 ). The coexistence of aceramic monumentality with unambiguous evidence of social stratification complicates long-standing periodization. Steward’s initial definition of the “Formative” rested on ceramics, mound–temple–priest complexes, and intensified agriculture (Steward, 1948 ; Willey & Phillips, 1958 ) subsequently foregrounded maize–manioc farming and sedentary village life. Yet the Late Archaic record reveals “Formative-like” political integration without pottery, highlighting the risk of reifying technological thresholds into universal cultural stages (D. A. Contreras, 2023 ; Watanabe, 2013 ). The conventional Formative (ca. 2200–200 cal BCE) is marked archaeologically by the introduction of ceramics, early metallurgy, and loom textiles—innovations often credited with propelling irrigation expansion, demographic packing, and settlement diversification (Lumbreras, 1989 ). Technological determinism, however, obscures the Late Archaic’s demonstrable capacity to generate complex institutions through non-material pathways, including integrative religion, nascent administration, and sophisticated resource management (Feldman, 1985 ; Hass & Creamer, 2006 ). Recent Bayesian modelling of radiocarbon sequences refines absolute chronologies and shows that ceramics frequently appear centuries after the consolidation of monumental architecture, suggesting that craft technologies amplified rather than initiated socio-political transformations. Monumentality throughout both periods served a dual mandate: as a stage for collective religious performance that forged supra-household cohesion, and as an instrument through which emergent elites materialized authority (Kembel & Rick, 2004 ; Rick, 2005 ). The continuity of architectural canons across the Late Archaic–Formative divide indicates that ideological commitments, not simply technological advances, underpinned Andean pathways to complexity. Taken together, the Late Archaic and Formative are best viewed as overlapping processes. The former demonstrates that monumental construction, ritual centralization, and hierarchical leadership could flourish independent of ceramic or textile technologies; the latter documents how subsequent innovations intensified and diversified these foundations. This Andean trajectory underscores the need for analytical frameworks that integrate ecology, economy, religion, and politics alongside material proxies, and it endorses Bayesian chronologies as a critical tool for disentangling the asynchronous cadence of technological and institutional change. The Kotosh Religious Tradition The KRT, named after the eponymous highland site of Kotosh near Huánuco, in the Andean central highlands, constitutes one of the earliest architecturally formalized ritual systems in the Central Andes. Active from the Late Archaic into the Formative, the KRT is defined by fire-focused ceremonies conducted within freestanding buildings that center on stone-lined hearths used for the controlled burning of offerings. Walls were plastered, floors stepped or split-level, and interior niches framed ritual paraphernalia (Fig. 01 ), marking these spaces as dedicated cult facilities rather than domestic dwellings (R. Burger & Salazar, 1980 , 1985 ; R. L. Burger & Salazar-Burger, 1986 ). Although a shared architectural structure united KRT communities, its expression varied with environment. On the hyper-arid central coast, settlements such as Caral and Huaricanga embedded KRT elements—central hearths, axial ventilation shafts, cyclic renovation—into monumental complexes of terraces and sunken plazas capable of hosting large congregations (Piscitelli, 2017b ; Ruth Shady, 2006 ; Ruth Shady, Haas, & Creamer, 2001 ). Highland centers such as Huaricoto and Piruru instead favored smaller, enclosed temples in which hearths facilitated more intimate ceremonies (Elizabeth Bonnier, 1983 ; Elisabeth Bonnier, 1988 ; R. Burger & Salazar, 1980 ). Regardless of scale, the recurrent dismantling, rebuilding, and deliberate burial of hearths articulated a doctrine of cyclical renewal and ancestral veneration. Each reconstruction materialized continuity, rooting contemporary ritual practice in a storied past. The sociopolitical reach of the KRT was as consequential as its religious program. By concentrating priestly authority around publicly visible hearth rituals, temple precincts forged communal identity while legitimizing emerging leaders who choreographed the ceremonies and controlled access to sacred fire. This “embedded religiousness” (Mesia-Montenegro & Sanchez-Borjas, 2023 )—the inseparability of cult practice and political power—became a hallmark of later Andean polities, which likewise fused religious and administrative roles within monumental architecture. Geography and space To date, twenty-three archaeological sites exhibiting KRT structures have been identified across the Central Andes, distributed over an estimated area of 80,000 km² (Fig. 2 ). Of these, sixteen sites (70%) have been dated, with the highest concentration observed in the Ancash region (nine sites) and Huánuco (four sites). Southern occurrences are documented in Lima (two sites), while northern examples are in Cajamarca (two sites). KRT sites demonstrate significant environmental variability, occupying distinct ecological zones: Coastal zones proximal to the littoral (e.g., Huaynuná, Bahía Seca, Gramalote, Macabalaca, El Paraíso, Alto Salaverry). Intermediate coastal valleys (e.g., Taukachi-Konkán, Pampa de las Llamas, Caral, Huaricanga, Buenavista). Eastern humid montane regions (e.g., Shillacoto, Piruru, Wairajirca, Kotosh) and Highland zones (e.g., La Seductora, La Galgada, El Silencio, Hualcayán, Acshicupoto, Huaricoto, Chavín de Huántar). This environmental diversity is reflected in the archaeological record, where KRT structures manifest in three primary contextual configurations: Autonomous architectural features (e.g., La Seductora, Huaricoto, Piruru). Central elements within complex architectural layouts (e.g., Kotosh, La Galgada, Caral, Acshicupoto). Peripheral components associated with large-scale architectural complexes (e.g., Huaricanga, Pampa de las Llamas, Taukachi-Konkán, Huaricanga, Chavín de Huántar). The variability observed in site placement and structural integration points to the adaptive strategies and sociocultural dynamics of prehispanic populations participating in the KRT tradition. Readers seeking site overviews and specifics should consult SI01. Methods To establish a robust absolute chronology for the KRT cultural complex, this study integrates 168 radiocarbon dates from associated archaeological sites (SI02). This study applies Bayesian chronological modeling in OxCal v.4.4.4, following strict radiocarbon calibration and statistical protocols (Bronk-Ramsey, 2017 ; Mesia-Montenegro, 2024 ; Napolitano et al., 2019 ). This approach addresses critical challenges in evaluating site contemporaneity, temporal overlap, and regional occupation patterns while systematically quantifying uncertainties inherent to radiocarbon datasets. Bayesian methods provide a statistically robust framework for synthesizing prior archaeological knowledge with radiocarbon likelihoods, thereby refining posterior age estimates beyond conventional calibration (Bronk-Ramsey, 2017 ; Dye, Buck, DiNapoli, & Philippe, 2023 ). Following established workflows (Brown, Anderson, Junge, & Duelks, 2023 ; Hamilton & Krus, 2018 ; Manning & Hart, 2019 ; Mesia-Montenegro, 2024 ; Sghinolfi, Millaire, & Roy, 2023 ), I structured models to treat each site as an independent Sequence within a hierarchical regional Phase, avoiding assumptions of temporal ordering. Site-specific boundaries were defined to reflect chronological breaks or transitions, with Markov Chain Monte Carlo (MCMC) sampling generating posterior distributions that integrate measurement errors and calibration curves. This methodology advances precision by formalizing uncertainty propagation, particularly for datasets with overlapping or sparse date ranges (Dye et al., 2023 ). To evaluate occupation dynamics across the study area, I implemented OxCal v.4.4.4’s Difference and Order (OCT) functions (Bronk Ramsey, 2021 ). By applying the Difference Command to compare initiation/termination boundaries between sites, I quantified intervals of potential overlap or hiatus (Fig. 3 and SI03), while OCT tested hypotheses of sequential occupation (SI04) (e.g., Site A preceding Site B) (S5) (Brown et al., 2023 ; Manning & Hart, 2019 ; Sghinolfi et al., 2023 ). This method avoids a priori assumptions of cultural or temporal continuity, instead allowing the data to probabilistically define regional patterns. Site chronologies are defined by their Start and End Boundaries (95.4% confidence intervals), derived from Bayesian posterior distributions. These boundaries represent the most probable temporal spans of occupation. Full tabulated results, including posterior density estimates, specifications, and diagnostic outputs are archived in SI05 to facilitate replication and reuse. This approach advances reproducibility in chronology-building by formalizing probabilistic tests of temporal hypotheses, a critical step for regional syntheses in archaeology (Dye et al., 2023 ; Mesia-Montenegro, 2024 ). Chronological Hygiene Current chronological frameworks in the study region exhibit a historical bias toward monumental sites, leading to systematic underrepresentation of smaller settlements in temporal reconstructions. Addressing this imbalance necessitates a dual focus in future research: (1) expanding radiocarbon datasets to incorporate underrepresented sites and (2) improving chronometric precision through adherence to modern sampling protocols (e.g., short-lived organic materials, stratigraphically secure contexts). All radiocarbon dates (168) were compiled from published literature (S02) and assessed using a four-tier chronological hygiene framework (Kidder & Grooms, 2024 ) (Table 1 ), which categorizes dates from rank 1 (highest reliability: e.g., short-lived taxa, secure stratigraphic association) to rank 4 (lowest: e.g., long-lived wood, uncertain provenance). This system, adapted from Napolitano et al. (Napolitano et al., 2019 ) and Krus (Krus, 2016 ), enables transparent prioritization of chronometric data (see S02, “CH” column for criteria). Calibration was conducted in OxCal v.4.4.4 with the SHCal13 curve (Hogg et al., 2020 ), the established standard for southern hemisphere regions (Marsh et al., 2018 ). Although Nesbitt et al. (Nesbitt, Asencios, & Tokanai, 2020 ) report minimal divergence between SHCal13, IntCal13, and mixed curves at Andean highland sites (e.g., Reparin), SHCal13 was uniformly applied across coastal and highland contexts to ensure methodological consistency. This approach facilitates direct comparability with regional studies while maintaining transparency. The model’s modular construction permits iterative updates as new calibration curves or data become available—a flexibility validated through prior applications to Andean coastal U-shaped structures (Mesia-Montenegro, 2024 ). Such adaptability supports open science objectives, enabling future revisions without compromising reproducibility or regional applicability. Table 1 Chronological hygiene levels (based on Kidder and Grooms, 2024 ). Level 01 Accurate dating requires the sample to come from a context that reliably dates the deposit, with sufficient information to link the sample's death to context formation. The dating must include detailed reporting, provenience information, and the laboratory's identification. Level 02 The dates rely on single-entity charcoal, charred material, or marine/freshwater shells not identified to taxon. Understanding of reservoir effects is partial, and evidence of deposition during context use is limited or unclear. The dating process must include detailed sample reporting, provenience information, and the processing laboratory's name and reference number. Level 03 The dates are based on unidentified single-entity charcoal, charred material, or marine/freshwater shells, with little to no understanding of reservoir effects. They may include radiometric dates on human bone apatite or samples that likely predate their recovery context, modeled as terminus post quem. These dates may also have incomplete or unclear contextual information. Level 04 The dates are based on multi-entity samples, like mixed charcoal, shells from multiple individuals, or bulk sediment, with unclear or compromised contextual relationships. This also includes cases where the material type is unspecified, the sample is contaminated, or fractionation corrections were not applied, especially for samples from maize, cane, or aquatic organisms Following Conolly’s guidelines (Connolly, 2006 ), any determination with a laboratory standard deviation greater than 90 years was discarded. I then applied the “chronological hygiene” (CH) scale, retaining only ranks 1–2. Together, these filters removed 62 of 168 determinations (37%), most of them from Huaricoto, Kotosh, Bahía Seca and Huacaloma, whose dates are imprecise. The resulting datasets underpin four alternative models (Table 02 ). Table 02 Bayesian models produced by OxCal according to their chronological hygiene standards and A model and overall values. Model A Model B Model C Model D All dates 168 dates σ ≤ 90 yr 141 dates Dates ranked 1 and 2. 106 dates Dates ranked 1 and 2. σ ≤ 90 yr A model, 58.9. A overall,68.4 A model, 32.0 A overall, 44.0 A model, 88.8. A overall, 84.7 A model, 85.4. A overall 86.9 Bayesian Modelling and Kernel Density Estimation Bayesian Chronological Modelling Four independent phased models were constructed, treating each archaeological site as a distinct Sequence within hierarchical regional Phases . This approach intentionally avoided imposing temporal ordering assumptions. Site initiation and termination boundaries were calculated using OxCal's Boundary function, which generates probability distributions for start and end dates at 95.4% confidence intervals through Markov Chain Monte Carlo (MCMC) sampling. This method integrates measurement errors, and calibration curve uncertainties to produce robust temporal ranges, preserving full probabilistic distributions rather than relying on simplified point estimates like medians (Bronk Ramsey 2009 ). Model Validation, Agreement Index and Outliers Model reliability was assessed using OxCal's Agreement Index (A-index). I required models to meet dual thresholds: an A_model value ≥ 60% indicating element-level coherence with prior constraints, and an A_overall value ≥ 60% confirming global structural validity (Hamilton & Krus, 2018 ; Ramsey, 1995 , 2009 ). Models failing these thresholds (e.g., Model B: A_overall = 44%) were rejected. Both indices must exceed a threshold of ≥ 60% to indicate robust agreement between the input data and modeled chronology. To ensure the reliability of Bayesian chronometric models in OxCal, it is essential to validate their statistical coherence using the A model and A overall model metrics. When constructing a Bayesian radiocarbon sequence, it is unrealistic to treat every determination as perfect. Laboratory uncertainty, residual contaminants, and stratigraphic mixing all produce occasional dates that diverge markedly from true age. To recognize this empirical reality the model employs OxCal’s general outlier framework, Outlier Model ("General", T(5), U(0.4), "t"). The Student-t kernel with five degrees of freedom supplies heavy tails, permitting sizeable deviations to be absorbed without dragging the entire sequence; in effect, most determinations behave as if Gaussian, but genuine outliers are granted the statistical room they require. The accompanying uniform prior U(0, 0.4) stipulates a conservative 0–40% chance that any single result is abnormal. This retains confidence that most dates are sound while allowing as many as two in five to be down-weighted if the likelihood function demands it. Applying the outlier tag “t” imposes uniform criteria, eliminating subjective exclusions and post-hoc adjustments. Consequently, the final chronology internalizes both the shared structure of the dataset and an explicit skepticism toward outliers, yielding phase boundaries that are more robust, transparent, and reproducible. Kernel Density Estimation Implementation I applied Kernel Density Estimation (KDE) to site-level posterior distributions using OxCal's KDE_Plot function (Bronk-Ramsey, 2017 ). This approach enhances interpretability of occupation phases (Fig. 04 ) while addressing known limitations of summed probability distributions (SPDs), where calibration curve irregularities and sampling biases generate artificial peaks (D. A. Contreras & Meadows, 2014 ; Michczynski & Michczynska, 2006 ). KDE smoothing reduces noise from calibration artifacts (Bayliss, Ramsey, Van der Plicht, & Whittle, 2007 ) and mitigates distortions from uneven temporal sampling (Chiverrell, Thorndycraft, & Hoffmann, 2011 ), clarifying genuine trends while suppressing spurious fluctuations. I selected KDE_Plot over KDE_Model for its non-intrusive visualization of existing Bayesian outputs. Unlike KDE_Model—which constructs independent probability distributions risking over-parametrization—KDE_Plot preserves the integrity of our phased models while enhancing trend clarity. This approach maintains contextual fidelity and chronological hygiene protocols without introducing redundant assumptions. Full model specifications and reproducible code are in SI06. Summed Probability Limitations While Summed Probability Distribution (SPDs) are commonly used as demographic proxies, I recognize their constraints: they primarily reflect research intensity rather than past population dynamics (Contreras & Meadows 2014 ), and calibration artifacts can artificially amplify certain periods (Michczyński & Michczyńska 2006). My phased KDE approach counters these issues by focusing on relative phase durations rather than absolute probability values, prioritizing chronological relationships over demographic inference. My priority is establishing robust chronological relationships (when phases start/end relative to each other) rather than making direct demographic inferences (how big the population was). Phase Delimitation To reconstruct the chronology of sites, I first employed the OxCal “Order” (OCT) matrix to evaluate pairwise start–start and end–end probabilities. By counting, for each site A, the number of other sites B for which P(Start A 0.50—and analogously for end boundaries—I derived a ranked sequence of site foundations (Table 03 ) (R code in SI07). Table 03 a. Model A. Ranked sequence of site foundations. Rank Event Sum Prob 1 Start Huaricanga 16.4096 2 Start Huaricoto 16.132 3 Start Pampa de las Llamas 14.9996 4 Start Acshicupoto 12.921998 5 Start Huaynuna 11.659698 6 Start La Galgada 10.871596 7 Start Piruru 10.771917 8 Start Caral 10.286102 9 Start Hualcayan 9.901971 10 Start Kotosh 8.841999 11 Start Buenavista 6.952022 12 Start El Paraiso 5.417186 13 Start Shillacoto 5.487267 14 Start Taukachi-Konkan 3.623591 15 Start Bahia Seca 3.168294 16 Start Gramalote 2.535116 17 Start Huacaloma 2.983 18 Start Chavin 0.0371 Table 03 b. Model D. Ranked sequence of site foundations. Rank Event Sum Prob 1 Start Huaricanga 11.8548 2 Start Pampa de las Llamas 10.92815 3 Start Acshicupoto 9.17235 4 Start Huaynuna 7.998738 5 Start La Galgada 7.273515 6 Start Piruru 7.202276 7 Start Caral 6.727266 8 Start Hualcayan 6.439196 9 Start Buenavista 4.08595 10 Start El Paraiso 2.986617 11 Start Taukachi-Konkan 1.821638 12 Start Gramalote 1.492781 13 Start Chavin 0.01684 Next, to delineate discrete chronological phases within this sequence, I extracted the 95.4% highest-posterior‐density (HPD) intervals for every phase boundary (both start and end) from the OxCal outputs (Fig. 05 ). To capture the uncertainty more accurately in my chronology of the KRT, I implemented a Monte Carlo–based kernel density estimation (KDE) of phase-breaks. Rather than collapsing each site’s calibrated radiocarbon HPD (highest posterior density) interval to a single midpoint, I repeatedly sampled one date from each interval and used those random draws to build a KDE of boundary density. By drawing uniformly from every Lower95.4–Upper95.4 bound and aggregating across sites, each individual KDE run represents one plausible realization of when cultural transitions occurred. I conducted ten thousand such replications, each time fitting a continuous density estimate (with a 100-year bandwidth) and extracting its first five local minima—the troughs that correspond to the boundaries between successive phases. Collecting these minima across all runs yields a distribution for each phase-break. I summarize each trough’s distribution by its median date and the 2.5–97.5% quantile interval. In Fig. 06 , the bold black curve is the median KDE; the surrounding gray ribbon marks the 95% envelope of all simulations; and the dashed vertical lines show the five median phase-break dates. For Model A, the Montecarlo KDE analysis revealed five pronounced troughs at approximately 3138, 2641, 2155, 1664 and 1180 cal BCE. For Model D, the R-based KDE analysis revealed five pronounced troughs at approximately 3011, 2414, 1842, 1305 and 1100 cal BCE (SI08) This approach—combining OxCal ordering, interval midpoints and Montecarlo kernel-density smoothing—provides a straightforward, reproducible workflow for defining discrete phases in poorly dated regions. The resulting phased chronology underpins our interpretation of the Kotosh Religious Tradition’s emergence, growth, consolidation, and decline. Results Radiocarbon Analysis Following accurate evaluation of Bayesian chronological models, the analysis was focused on Models A and D due to their superior statistical coherence and reliability. Model A yielded agreement indices, with an A model value of 58.9 and an A overall value of 68.4, while Model D demonstrated concordance, achieving an A model of 85.4 and A overall of 86.9. In contrast, Model B, despite employing radiocarbon dates with tighter measurement uncertainties (σ), produced critically low agreement indices (A model = 32; A overall = 44), rendering it statistically unreliable for robust chronological inference. Although Model C exhibited an acceptable agreement (A model = 88.8; A overall = 84.7), its chronological hygiene standards were surpassed by the Caral model, which also achieved higher A model values (Table 2 ). While the A value for Model A is (58.9) falls slightly below the conventional 60% threshold, its selection is justified by the model’s strong overall agreement (A overall = 68.4). Sensitivity analysis confirmed that removing this sample did not significantly alter the phase boundaries, supporting its retention. This selective focus Models A and D is justified by their adherence to stringent chronometric protocols, which are critical for high-resolution temporal reconstructions in Andean archaeology. While dataset reduction introduces trade-offs in sample size, this aligns with best practices for chronological hygiene (Kidder & Grooms, 2024 ; Napolitano et al., 2019 ), emphasizing precision in occupation-phase modeling. While summarizing the findings of models A and D, in Table 4 and providing all the data as supplementary information for scholars to review and compare interpretations, I will focus on examining Models A and D in the following sections. The visualization details for both models and their interactions can be seen in Fig. 07 . Table 04 a . Model A, stages, and phases Stages Years BC Phase Sites Decline 1200–300 BCE Phase 06 Huacaloma, Piruru, Chavín, Huaricoto Consolidation 1700 − 1200 BCE Phase 05 Piruru, Hualcayán, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Bahía Seca, Taukachi-Konkán, Huacaloma, Gramalote 2200 − 1700 BCE Phase 04 Huaricoto, Huaynuná, Piruru, Hulcayán, Caral, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso Expansion 2600 − 2200 BCE Phase 03 Huaricanga, Huaricoto, Pampa de las Llamas, Acshicupoto, Huaynuná, La Galgada, Piruru, Caral, Hualcayán, Kotosh 3100 − 2600 BCE Phase 02 Huaricanga, Huaricoto, Pampa de las Llamas, Acshicupoto, Huaynuná, La Galgada Onset 3600 − 3100 BCE Phase 01 Huaricanga and Huaricoto Table 4 b. Model D, stages, and phases Stages Years BC Phase Sites Decline 1100–500 BCE Phase 06 Chavin Consolidation 1300 − 1100 BCE Phase 05 Piruru, Hualcayán, Pampa de las Llamas, El Paraíso, Gramalote 1800 − 1300 BCE Phase 04 Huaynuná, Piruru, Hualcayán, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Taukachi-Konkán, Gramalote Expansion 2400 − 1800 BCE Phase 03 Huaricanga, Huaynuná, Piruru, Hualcayán, Pampa de las Llamas, Caral, La Galgada, Buenavista 3000 − 2400 BCE Phase 02 Huaricanga, Pampa de las Llamas, Huaynuná, Piruru, Acshicupoto and Caral Onset 3600 − 3000 BCE Phase 01 Huaricanga Model A As previously stated, this model encompasses the complete dataset. The A-Model’s values are 58.9 and 68.4. As explained before, the statistics for A values render the model acceptable (Fig. 08 ). Onset Stage (3600 − 3100 BCE) This stage is represented by the emergence of early KRT structures across the Central Andes. Phase 01 (3600 − 3100 BCE) Only two ceremonial centers fall within the earliest span of the Kotosh Religious Tradition: Huaricanga on the lower Fortaleza-Supe divide and Huaricoto in the upper Santa (Ancash) drainage. Architecturally, the two sites contrast sharply. Huaricanga comprises multiple KRT rooms arranged beside large platform buildings and circular sunken courts, attesting to substantial labour mobilisation and sophisticated planning. Huaricoto, by comparison, is smaller and its KRT rooms lack the massive stone walling seen on the coast. The greater investment evident at Huaricanga implies stronger managerial capacities and more reliable access to construction resources, signalling an early concentration of ritual authority in the lower valleys. Together, these two centers mark the initial appearance of KRT architectural and ideological motifs in both coastal and highland settings, laying the foundations for the subsequent expansion documented in later phases. Expansion Stage (3100 − 2600 BCE) This stage is represented by the expansion of KRT structures into the coast, highlands, and Andean mountains. Phase 02 (3100 − 2600 BCE) During this interval, seven contemporaneous centers sustained KRT ritual activity: the long-occupied sites of Huaricanga and Huaricoto; the coastal enclave of Pampa de las Llamas; the littoral complex of Huaynuná; two newly founded high‐altitude sites at Acshicupoto and La Galgada (Ancash). The material record reveals a pronounced territorial expansion. Along the central coast, Pampa de las Llamas and Huaynuná extend the KRT into littoral settings; concurrently, in the Cordillera Negra, the founding of Acshicupoto and La Galgada attests to the tradition’s sustained penetration into Ancash highlands. La Galgada, surpasses the earlier highland site at Huaricoto in both scale and elaboration, signaling the ascendant prestige of KRT ceremonialism beyond the coast. Phase 03 (2600 − 2200 BCE) There are ten centers within this 400-year span: Huaricanga, Huaricoto and Pampa de las Llamas; Acshicupoto, Huaynuná, La Galgada and Piruru; and three newcomers—Caral, Hualcayán and Kotosh. Archaeologically, Phase 03 extends the spatial growth documented in Phase 02 but introduces markedly more elaborate ceremonial architecture. Caral’s monumental platform mounds, Hualcayán’s terraces and Kotosh’s sculpted temples all signal a step-change in construction scale and ritual complexity. Their near-synchronous emergence across distinct ecological zones—lower Supe valley, high Callejón de Huaylas and upland Huánuco—suggests intensified interregional communication and the consolidation of shared canons. Phase 03 blends long-standing coastal sites with new monumental highland counterparts into an increasingly integrated ceremonial sphere. Consolidation (2200 − 1200 BCE) This stage is represented by the expansion of KRT structures into the coast, highlands, and Andean mountains. Phase 04 (2200 − 1700 BCE) During this interval, ten centers maintained almost synchronous ritual activities, Huaricoto, Huaynuná, Piruru, Hualcayán, Caral, Kotosh, La Galgada, Pampa de las Llamas, Buenavista and El Paraiso. The integration of KRT elements into the U-shaped complex at El Paraíso exemplifies the transmission of ritual norms into densely settled coastal zones, marking a critical shift from a highland-confined phenomenon to an interregional ceremonial network. This phase of consolidation coincides with paleoclimatic proxies indicating heightened ENSO variability (Caramanica, Quilter, Huaman, Villanueva, & Morales, 2018 ), suggesting that episodic climate perturbations fostered supra-local cooperation. Phase 05 (1700 − 1200 BCE) Radiocarbon results indicate that eleven centers remained active during this interval: Piruru, Hualcayán, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Bahía Seca, Taukachi-Konkán, Huacaloma and Gramalote. This phase represents the moment at which KRT ceremonialism achieved maximal geographic integration—establishing a unified ritual repertoire across both the Andean highlands and the central–north coast and laying the ideological groundwork for the tradition’s subsequent pan-Andean expansion. Coastal nodes such as Pampa de las Llamas and El Paraíso sustained large-scale construction and communal ritual activities, demonstrating persistent administrative capacity. In the highlands, the emergence of Huacaloma attests to the continued resonance of KRT ideology and its northward dissemination into Cajamarca. Decline Stage (1200 − 300 BCE) This stage is characterized by the substantial reduction of KRT sites in the Andes. Phase 06 (1200 − 300 BCE) By Phase 06, the KRT enters a period of contraction and transformation. Only a handful of core centers—most notably Huacaloma, Piruru, Huaricoto, and Chavín—continue with the KRT. Across the broader landscape, KRT is repurposed or abandoned. Across the Central Andes, the widespread abandonment of U-shaped temple complexes and the political contraction of Chavín de Huántar (Mesia-Montenegro, 2024 ) mark the terminal dissolution of KRT as an interregional phenomenon. At Chavín, KRT architectural elements are confined to peripheral courts, indicating that KRT assumed a subordinate position within an increasingly pluralistic religious milieu. This interval coincides with an intensified ENSO (D. Sandweiss, Shady, Moseley, Keefer, & Ortloff, 2009 ; D. H. Sandweiss et al., 2001 ) and a major Ancash earthquake ca. 550 BCE events that destabilized agrarian production and eroded coastal elites’ capacity for mobilizing large labor forces. Stable-isotope analyses from human and faunal remains in the Supe Valley indicate that, after ca. 500 BCE, climatic variability and agrarian stress precipitated sociopolitical instability: collapsing crop yields, escalating competition for resources, and eroded elite capacity to sustain centralized governance (Pezo-Lanfranco et al., 2022 ). This period of destabilization coincides also with the decline of Chavín de Huántar’s pan-Andean influence (Rick, 2008 ; Rick et al., 2010 ). The Kotosh Model reveals a dynamic trajectory characterized by spatial expansion, architectural innovation, and cultural integration. Rigorous chronological and analytical methods (including OCT and Difference Command analyses) underpin the identification of sequential patterns in site emergence, expansion, consolidation, and decline. The evolution of the KRT—from its early ceremonial centers to its eventual integration and regional diversification—reflects complex interactions among environmental, social, and ideological factors over three millennia. Model D As previously noted, this model analyzes dates classified under chronological hygiene levels 1–2, excluding those with standard deviations exceeding ninety. With A model values of 95.9 and 95.0 —surpassing the 60-threshold required for acceptability, it demonstrates robust performance. Furthermore, this model achieves the highest A-model value among all four models produced, solidifying its position as the most statistically reliable version (Fig. 09 ). Onset Stage (3600 − 3000 BCE) This stage is represented by the emergence of early KRT structures across the Central Andes. Phase 01 (3600 − 3000 BCE) This initial phase is demarcated by Huaricanga, located in the mid-Pativilca Valley, situated in the north-central Andean coast. As mentioned before, at Huaricanga, KRT structures were not placed in a prominent position but next to larger mounds and circular sunken courts. Expansion Stage (3000 − 1800 BCE) This stage is represented by the expansion of KRT structures into the coast and highlands. Phase 02 (3000 − 2400 BCE) This phase marks the KRT’s first coastal–highland expansion. North-coastal Huaynuná and south-coastal Caral adopt canonical rectangular temples with central hearths and wall niches, while Acshicupoto carries the tradition upslope, signaling emergent inter-valley networks. Yet coastal centers retain distinctive local character: at Caral, KRT temples dominate the settlement core, whereas at Huaricanga they remain subsidiary outbuildings flanking larger mounds and sunken-court complexes. Phase 03 (2400 − 1800 BCE) This period marks a critical point in the evolution of the KRT, with the emergence of Piruru, La Galgada, Buenavista, Hualcayán and Pampa de las Llamas. La Galgada is distinguished by its multi-level temples featuring ventilated hearths and intricately carved niches, reflecting a high degree of ritual specialization. A similar, albeit less pronounced, expression is observed at Hualcayán, situated south of La Galgada. The contemporaneous occupation of Caral suggests that interactions between highland and coastal societies were limited, as each maintained distinct architectural expression. In contrast, sites such as Acshicupoto did not incorporate KRT elements despite following their established chronological trajectories. Additionally, Buenavista emerges as the southern expression of the KRT and Pampa de las Llamas emerges in the Casma valley. Consolidation Stage (1800 − 800 BCE) This stage is represented by the consolidation of KRT structures into the coast, highlands, and Andean mountains. Phase 04 (1800 − 1300 BCE) While long-standing KRT centers—Huaynuná, Piruru, Buenavista, Pampa de las Llamas, and Hualcayán—remained active, the establishment of newly monumental nodes such as El Paraíso signals a fresh wave of ritual investment. The simultaneous persistence and expansion of these sites point to a moment of heightened socio-political integration in which ceremonial architecture functioned as a locus of collective identity and coordination. This integrative impulse likely emerged in response to climatic perturbations linked to ENSO variability and attendant demographic shifts, which would have intensified the demand for supra-local cooperation and shared ideological frameworks (Caramanica et al., 2018 ; D. Sandweiss et al., 2009 ; D. H. Sandweiss et al., 2001 ). Phase 05 (1300 − 1100 BCE) During the late consolidation phase, only Piruru, Hualcayán, Pampa de las Llamas, El Paraíso, and Gramalote, continue active. Collectively, this pattern signals a pronounced regional realignment, reflecting shifting social priorities and adaptive responses to external pressures. Decline Stage (800 − 500 BCE) This stage is marked by a significant decline in KRT sites across the Andes. Phase 06 (800 − 500 BCE) In the last phase (c. 600–300 BCE) the KRT fades as a coherent tradition. Only residual temples at Chavín de Huántar, set apart from the main complex, keep its forms alive. This interval coincides with a severe El Niño and a large earthquake (~ 550 BCE) in Ancash (Rick et al., 2010 ). Isotope data from the Supe Valley reveal food stress and growing competition, eroding elite power (Pezo-Lanfranco et al., 2022 ). Central-coast U-shaped centers were abandoned, and Chavín’s broader influence collapsed (Mesia-Montenegro, 2024 ). Environmental shocks and social turmoil thus framed the final retreat of KRT ideals. In summary, the data delineates a trajectory of regional experimentation, adaptation, and eventual synthesis within the Andean cultural landscape. The robust performance of the radiocarbon model supports these chronological phases, which collectively reveal the dynamic evolution of the Kotosh Religious Tradition—from its origins at Huaricanga, through regional expansion and formalization of ritual spaces, to its eventual decline and legacy in subsequent cultural expressions. Discussion The KRT represents a pivotal phenomenon in the emergence of socio-religious complexity in the Central Andes. By integrating Bayesian chronological modeling with a geographically expansive dataset, this study challenges long-standing assumptions about the unidirectional diffusion of ritual practices and redefines the spatiotemporal dynamics of the KRT. The results reveal a near-synchronous emergence of the KRT across ecologically distinct regions (3600 Cal BCE), sustained ritual continuity through the Late Archaic and Formative periods, and multidirectional cultural exchange that reshaped regional belief systems. These findings call for a reassessment of the mechanisms behind religious innovation, the influence of environmental adaptation on cultural development, and the relationship between religion and socio-political organization in early Andean societies. Reassessing Cultural Diffusion and Regional Agency Model A supports the simultaneous emergence of KRT-associated structures in both coastal (Creamer et al., 2013 ; Piscitelli, 2014 , 2017a , 2017b ) and highland regions(Elizabeth Bonnier, 1997 ; R. Burger, 1992 ; R. L. Burger & Salazar-Burger, 1986 ) (3600–3000 Cal BCE) which in turn refutes models advocating for a unidirectional spread of religious practices. Instead, Bayesian models support multiregional syncretism, wherein shared ritual principles—such as fire-centric ceremonies and ventilated hearths—were adapted to local ecological and social contexts. While Model D isolates Huaricanga as the sole bearer of the KRT (peripheral to the main architectural volumes), Phase 02 of Model D reinforces a multidirectional network of KRT sites that not only expanded to Caral but also to the highlands and eastern mountains (Piruru). Coastal manifestations of the KRT were characterized by the integration of ritual elements into expansive monumental complexes, designed to facilitate collective ceremonial practices and consolidate elite authority—a pattern paralleled, albeit at a comparatively reduced scale, in select highland sites such as La Galgada, Acshicupoto, and Hualcayán and probably Kotosh. In contrast, other highland sites (e.g., Huaricoto, Piruru, and the northern highland site La Seductora) prioritized smaller-scale, heart-centric structures situated within communally oriented landscapes. The differences in architecture and site organization reveal that highland communities actively reshaped KRT ritual practices rather than merely copying them. Instead of being passive imitators on the margins, these communities played a significant role in reworking the tradition, tailoring its core ideas to their local environments and social needs while retaining unique ritual practices. This agency challenges older theories that view cultural practices as spreading outward from a sole source, emphasizing instead a network of interconnected regions that collectively shaped the KRT across the Andes. Bayesian models suggest a dynamic ideological network facilitated by cross-regional interaction, possibly through pilgrimage, resource exchange, or seasonal mobility (Mesia-Montenegro & Sanchez-Borjas, 2023 ). The presence of marine shells at highland Huaricoto, La Galgada and Huaricanga, and highland-style niches at coastal Caral (Ruth Shady, 2004 , 2006 ) materializes this reciprocity, illustrating how ritual spaces functioned as nodes in a pan-Andean exchange system. Such multidirectional influence aligns with Granovetter’s theory of “weak and strong ties”, wherein intermittent interactions between distinct groups foster trust and cultural hybridization without eroding regional identities (M. S. Granovetter, 1973 ). KRT sites functioned as pivotal hubs for rituals that interconnected local communities (characterized by strong ties) and broader regional networks (defined by weak ties). These sites operated as nodes within a social and ritual network, bridging otherwise fragmented groups through shared ceremonial participation. Standardized architectural elements—such as central hearths and ventilation shafts—reflect a shared ritual lexicon that facilitated communication and trust among diverse populations, enabling cross-group cohesion. Within this framework, strong ties—marked by close emotional bonds, frequent interaction, and mutual trust—fostered solidarity within tight-knit groups. However, their dense, overlapping social circles often limited exposure to novel ideas due to redundant information flows. Conversely, weak ties (per Granovetter’s theory) provided access to non-redundant information, acting as critical bridges for innovation and intergroup exchange (M. Granovetter, 2017 ) . A compelling dynamic emerges if KRT leaders strategically cultivated weak ties with peers in other communities. As brokers of social capital, leaders could selectively harness weak ties to gather external innovations or knowledge, then integrate these into their local strong-tie networks. This dual role allowed leaders to regulate information flow, modulating the openness of their communities to external influences while maintaining internal cohesion. By curating weak-tie connections, leaders balanced the introduction of new ideas with the preservation of traditional practices, thereby shaping the adaptive capacity and cultural trajectory of their groups (M. S. Granovetter, 1973 ). In this sense, Granovetter’s theory underscores that diversity in social connections—not just their closeness—drives innovation, opportunity, and resilience. Embedded Religiousness: Ritual as Social and Economic Infrastructure The concept of embedded religiousness is essential for understanding the lasting influence of the Kotosh Religious Tradition (KRT) in the Andean region. This framework posits that religious practices were not separate from social and economic structures but were instead deeply integrated into them. Within this system, religion functioned as a foundational mechanism for organizing authority, structuring social relationships, and directing economic activities. KRT sites exemplify this integration, serving as multifunctional nodes where religious, political, and communal activities converged. Religious institutions provided a legitimizing framework for authority, embedding power within shared rituals and symbols. This, in turn, reinforced social cohesion, facilitated cooperation, and sustained hierarchical structures (Hayden, 1995 , 2018 ; Hayden & Villeneuve, 2010 ; Mesía-Montenegro, 2018 ). Beyond their ritual significance, these sites also played crucial economic roles, acting as hubs for resource redistribution, labor coordination, and elite legitimization. The theoretical foundation of embedded religiousness aligns, again, with Granovetter’s concept of embeddedness in economic sociology, which argues that economic transactions are governed by social norms and trust rather than purely rational self-interest. Similarly, in the Andean context, religious institutions—such as those associated with the KRT—functioned as authoritative centers that structured both social and economic life. By providing codified knowledge of rituals, these institutions conferred power on elites, who leveraged religious frameworks to mobilize labor and consolidate status (M. Granovetter, 1985 , 2017 ) . Bayesian statistical models support this perspective by demonstrating the long-term continuity of ritual practices across diverse ecological zones. For example, the cyclical renovation of ceremonial hearths at Late Archaic and Formative sites from the Andean coast and highlands suggests a shared ideology of renewal that transcended environmental and temporal boundaries. These practices were operationalized through large-scale collective labor projects—such as quarrying stones for platform mounds or maintaining ceremonial fires—where economic activities were inseparable from religious frameworks. This interplay between religion and economy is further illuminated by Polanyi’s concept of the “embedded economy,” (Polanyi, 2001 ) which argues that economic exchange was governed by cultural norms rather than market forces. While Polanyi emphasized that economies are embedded in social relations, the concept of embedded religiousness proposes that in the Andean world, religion—not the economy—was the central organizing force. Religious institutions dictated key aspects of economic life, including resource allocation, labor mobilization (e.g., communal construction projects), and the formation of social hierarchies. For instance, the circulation of prestige goods at La Galgada—such as spondylus ornaments—was likely facilitated through religious networks, reflecting a ritualized economy where sacred practices structured exchange (Grieder, Bueno, Smith Jr, & Malina, 2012 ; Washburn et al., 2020 ). In this system, religious authority shaped not only symbolic meaning but also material transactions, reinforcing social differentiation through control over sacred knowledge and access to valued goods (Mesia-Montenegro & Sanchez-Borjas, 2023 ) . The concept of embedded religiousness refines Polanyi’s critique of market fundamentalism by asserting that religion, rather than economic forces, constituted the overarching system in ancient Andean societies. Just as Polanyi cautioned against the segregation of economies from social structures, it is crucial not to treat religion as an isolated sphere. Instead, religion was the central axis around which authority and economic organization were woven into a unified cultural framework. Ideology, Authority, and the Institutionalization of Religion The KRT’s architectural and ritual norms provided a template for institutionalizing religious authority. At coastal centers, the integration of KRT structures into monumental complexes (e.g., Caral, the Casma valley) suggests that emerging elites co-opted ritual spaces to consolidate power. The restricted access to coastal KRT altars—contrasted with open plazas for communal ceremonies—reflects a hierarchical ritual system where elites mediated between religious and human realms (Hayden, 1995 , 2001 , 2018 ; Hayden & Villeneuve, 2010 ). Conversely, highland sites like Huaricoto, La Seductora and Piruru emphasize repeated hearth renovations and communal offerings, indicating collective stewardship of ritual knowledge (Elizabeth Bonnier, 1997 ; Mesia-Montenegro & Sanchez-Borjas, 2023 ). Bayesian models further illuminate how KRT practices facilitated ideological synergy during the Formative period (1800–200 BCE). The late persistence of KRT elements at Chavín de Huántar—a site renowned for its pan-regional influence—demonstrates the tradition’s enduring symbolic capital. Here, the KRT structure was incorporated into a peripheral location, suggesting that earlier rituals were either supplanted or strategically retained to legitimize Chavín’s authority (D. Contreras, 2010 ; Rick, 2005 , 2008 ). This duality underscores the KRT’s role as both a foundational tradition and a malleable ideological tool, adaptable to shifting political landscapes. Conclusions Three questions were posed at the beginning of this paper: how can Bayesian chronological modeling in OxCal, along with rigorous chronological hygiene protocols, clarify the origins and dissemination of the Kotosh Religious Tradition (KRT). How can Bayesian chronological modeling (via OxCal), combined with stringent chronological hygiene protocols, elucidate the origins, and spread of the Kotosh Religious Tradition (KRT)? What temporal overlaps exist between early coastal KRT monumental complexes and highland ritual practices, and how do these overlaps inform patterns of cultural coexistence or ideological change? Can Bayesian analysis substantiate bidirectional cultural transmission between the coast and highlands, thereby challenging linear diffusion theories? Bayesian Chronological Modeling and Chronological Hygiene Protocols Bayesian modeling via OxCal, combined with stringent chronological hygiene protocols, enhanced the precision of dating the Kotosh Religious Tradition (KRT) by integrating 168 radiocarbon dates from sixteen sites. Chronological hygiene excludes low-reliability dates (e.g., large σ or unclear contexts), focusing on high-quality data (e.g., clear, and traceable contexts). This approach reduced uncertainty, enabling robust phased models that revealed the KRT emerged simultaneously on the central coast and highlands by 3500 Cal BCE. The analysis demonstrated rapid coastal innovation (e.g., monumental complexes) and concurrent highland adoption with localized adaptations (e.g., smaller heart-centered structures). By resolving ambiguities in temporal sequencing, Bayesian methods provided a unified chronology, challenging assumptions of unidirectional diffusion and highlighting regional synchronicity in KRT origins. This Bayesian hygiene workflow can be adapted to other under-dated contexts to assess whether similar synchronicity patterns occurred elsewhere. Temporal Overlaps and Cultural Coexistence: The Bayesian models identified significant temporal overlaps between coastal and highland KRT sites. Coastal monumental complexes (e.g., Huaricanga) and highland ritual practices (e.g., Huaricoto) emerged contemporaneously (3600–3000 cal BCE). Coastal sites prioritized large-scale ceremonial architecture (e.g., sunken plazas), while highland sites emphasized intimate fire ritual spaces. These overlaps indicate cultural coexistence rather than displacement, with regions adapting KRT to ecological and sociopolitical contexts. The sustained overlap, even well into the fifth phase, reflects ideological synergy, where shared ritual elements persisted alongside regional divergences. Bidirectional Cultural Transmission: Bayesian chronological modeling challenges unilinear diffusion paradigms, demonstrating cultural transmission between coastal and highland KRT sites. The analysis reveals that highland communities innovatively adapted KRT ritual principles—such as specialized ventilation systems—into multifunctional administrative and ceremonial spaces, which were later reincorporated into coastal architectural repertoires. This reciprocity materialized in shared features (e.g., ritual hearths, wall niches) and overlapping site chronologies, reflecting sustained interaction rather than unidirectional influence. Persistent weak-tie networks (sensu Granovetter) between regions facilitated the integration of localized “strong-tie” practices into a broader ideological framework. By situating highland regions as dynamic co-responsible of KRT development, the study underscores environmental diversity and cross-regional mediation as catalysts for ritual and organizational complexity in the pre-Hispanic Andes. Finally, the KRT emerged as a pan-Andean ritual and architectural phenomenon, characterized by ceremonial structures with central hearths, ventilated chambers, split-level floors, and plastered walls. Its evolution reflects adaptive syncretism between highland religious practices and coastal monumentality, shaped by environmental, social, and ideological dynamics. Declarations Author Contribution Christian Mesía-Montenegro: Writing – review & editing. Visualization, Validation, Supervision, Software, Resources, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization. Acknowledgement To all researchers who openly share their data, advocate open science, and open data practices, and to the reviewers whose feedback has enhanced the quality of this paper. To the Universidad Privada del Norte which provided time and resources for undertaking this research. Any mistakes are entirely my own. Data Availability All data, OxCal and R codes are provided as supplementary information. References Bayliss A, Ramsey CB, Van der Plicht J, Whittle A (2007) Bradshaw and Bayes: towards a timetable for the Neolithic. Camb Archaeol J 17(S1):1–28 Bonnier E (1983) Piruru: Nuevas Evidencias de la Ocupación Temprana en Tantamayo, Perú. Gaceta Arqueológica Andina 8:8–10 Bonnier E (1988) Arquitectura precerámica en la cordillera de los Andes, Piruru frente a la diversidad de los datos. Anthropologica del Departamento de Ciencias Sociales 6(6):335–361 Bonnier E (1997) Preceramic Architecture in the Andes: The Mito Tradition. In E. Bonnier & H. 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Centura, Lima Shady R (2006) America’s First City? The Case of Late Archaic Caral. In: Isbell WH, Silverman H (eds) Andean Archaeology III: North and South. Springer US, Boston, MA, pp 28–66 Shady R, Haas J, Creamer W (2001) Dating Caral, a Preceramic Site in the Supe Valley on the Central Coast of Peru. Science 292(5517):723–726. 10.1126/science.1059519 Steward J (1948) A Functional-Developmental Classification of American High Cultures. In: Bennett W (ed) A Reppraisal of Peruvian Archaeology: Memoirs of the Society for American Archaeology. Society for American Archaeology and the Institute of Andean Research, Wisconsin, pp 103–105 Washburn E, Nesbitt J, Burger R, Tomasto-Cagigao E, Oelze VM, Fehren-Schmitz L (2020) Maize and dietary change in early Peruvian civilization: Isotopic evidence from the Late Preceramic Period/Initial Period site of La Galgada, Peru. J Archaeol Science: Rep 31:102309 Watanabe S (2013) Estructura en los Andes antiguos. Editorial Shumpusha, Yokohama Willey G, Phillips P (1958) Method and theory in American archaeology. University of Chicago Press, Chicago Additional Declarations No competing interests reported. Supplementary Files SI01.docx SI02.xlsx SI03.xlsx SI04.xlsx SI05.xlsx SI06.txt SI07.txt SI08.txt Cite Share Download PDF Status: Published Journal Publication published 02 Dec, 2025 Read the published version in Archaeological and Anthropological Sciences → Version 1 posted Editorial decision: Revision requested 28 Jul, 2025 Reviews received at journal 23 Jul, 2025 Reviewers agreed at journal 18 Jul, 2025 Reviewers invited by journal 13 Jul, 2025 Editor assigned by journal 16 Jun, 2025 Submission checks completed at journal 16 Jun, 2025 First submitted to journal 14 Jun, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6896121","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":485243183,"identity":"e2947e76-54c1-4d23-841d-67a7b79f28dc","order_by":0,"name":"Christian Mesía-Montenegro","email":"data:image/png;base64,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","orcid":"","institution":"Private University of the North","correspondingAuthor":true,"prefix":"","firstName":"Christian","middleName":"","lastName":"Mesía-Montenegro","suffix":""}],"badges":[],"createdAt":"2025-06-15 02:38:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6896121/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6896121/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s12520-025-02370-9","type":"published","date":"2025-12-02T15:57:39+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":87046401,"identity":"3dcab43b-9d00-41c6-9486-30b9d0ebf6a2","added_by":"auto","created_at":"2025-07-18 14:37:57","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":107209,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKRT architectural examples.\u003c/strong\u003e KRT sites of Macabalaca and La Seductora\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/1a8f7ac470f9d5b21f588e90.jpg"},{"id":87046402,"identity":"d45c35f4-5c22-4137-9937-a9ad7ae4b88c","added_by":"auto","created_at":"2025-07-18 14:37:57","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":268711,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution of dated and not dated KRT sites.\u003c/strong\u003e Dated sites are in red dots and non-dated sites in green ones.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/490e8bfa2a8eeaab22ae7bdc.jpg"},{"id":87048220,"identity":"cc160288-34cd-402c-a53a-cb83eaa40c85","added_by":"auto","created_at":"2025-07-18 14:45:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":241244,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDifference Command Graphic Outputs. \u003c/strong\u003eModels A and D Difference outputs.\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/06d82d03202cc077bd904cfa.jpg"},{"id":87049724,"identity":"20e619c5-bcd1-42f1-b085-f07259375a01","added_by":"auto","created_at":"2025-07-18 14:53:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":195937,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKernel Density Estimations.\u003c/strong\u003e Model A and D KDE. Colors show chronological stages.\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/40d80f53983e127b5c796b98.jpg"},{"id":87048223,"identity":"e12502b3-9449-4032-a5ca-692476741cc4","added_by":"auto","created_at":"2025-07-18 14:45:57","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":153602,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. Model A, HPD intervals\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb\u003c/strong\u003e. Model D, HPD intervals\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/8a39c2bcab21e108090964f8.jpg"},{"id":87048228,"identity":"e94fcdce-163f-4401-b31b-f89b343d16f6","added_by":"auto","created_at":"2025-07-18 14:45:58","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":118901,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. Model A, Monte Carlo KDE phase break distributions\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb\u003c/strong\u003e. Model D, Monte Carlo KDE phase break distributions\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/6ae1d922d85298ad1eabb90e.jpg"},{"id":87046428,"identity":"26820a15-6862-44be-8471-9937879f82d4","added_by":"auto","created_at":"2025-07-18 14:37:58","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":221270,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBayesian Radiocarbon modellings.\u003c/strong\u003e A and D models. Colors indicate chronological stages. Gray shades point to modelled dates, black shades to unmodelled dates.\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/5729b159aacfb17e3f6c7333.jpg"},{"id":87046424,"identity":"590c20e9-a5f2-42b6-a643-9b83888c2b6c","added_by":"auto","created_at":"2025-07-18 14:37:58","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":148261,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eModel A chronological distribution.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Picture8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/7fc72a5978a6ddcef6718665.jpg"},{"id":87046455,"identity":"f079c098-2c5b-4023-b00f-c83ce319b592","added_by":"auto","created_at":"2025-07-18 14:37:59","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":146706,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eModel D chronological distribution\u003c/strong\u003e.\u003c/p\u003e","description":"","filename":"Picture9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/3f9e21226060db25a6308159.jpg"},{"id":97723841,"identity":"d518adfc-3eb0-49ff-8dc2-7f496c537b7b","added_by":"auto","created_at":"2025-12-08 16:08:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2728316,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/372b17a6-89da-4758-a67b-12f98bf8f4fa.pdf"},{"id":87046405,"identity":"b4b9a332-beec-4970-8016-112d986257b2","added_by":"auto","created_at":"2025-07-18 14:37:57","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":74381,"visible":true,"origin":"","legend":"","description":"","filename":"SI01.docx","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/b682696e0528a212ca44a215.docx"},{"id":87046412,"identity":"a27f44ce-0d43-4ee0-abbc-2d20198bd4f0","added_by":"auto","created_at":"2025-07-18 14:37:58","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":64968,"visible":true,"origin":"","legend":"","description":"","filename":"SI02.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/4712bad6d603db855ac5a9ae.xlsx"},{"id":87048221,"identity":"b17495ee-6693-4f69-af76-a4b534e2e02b","added_by":"auto","created_at":"2025-07-18 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14:53:58","extension":"xlsx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":56249,"visible":true,"origin":"","legend":"","description":"","filename":"SI05.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/2482946ded5f8f5ed4568d3a.xlsx"},{"id":87048227,"identity":"e4c49d34-cdf2-45c3-9615-81535a832478","added_by":"auto","created_at":"2025-07-18 14:45:58","extension":"txt","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":107864,"visible":true,"origin":"","legend":"","description":"","filename":"SI06.txt","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/82472490702275a905d8276b.txt"},{"id":87046450,"identity":"59f2f012-f46d-44b6-8823-3954b931a800","added_by":"auto","created_at":"2025-07-18 14:37:59","extension":"txt","order_by":7,"title":"","display":"","copyAsset":false,"role":"supplement","size":4743,"visible":true,"origin":"","legend":"","description":"","filename":"SI07.txt","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/c2981d84b1b98c05fee4826e.txt"},{"id":87046438,"identity":"a4672457-028d-4b37-8197-70c19de8e5cc","added_by":"auto","created_at":"2025-07-18 14:37:58","extension":"txt","order_by":8,"title":"","display":"","copyAsset":false,"role":"supplement","size":9449,"visible":true,"origin":"","legend":"","description":"","filename":"SI08.txt","url":"https://assets-eu.researchsquare.com/files/rs-6896121/v1/da570bd1fea5f2cf896ab1ec.txt"}],"financialInterests":"No competing interests reported.","formattedTitle":"Time, Ritual, and Bayesian Reasoning: Charting the Andean Kotosh Religious Tradition","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe Kotosh Religious Tradition (KRT) represents a pivotal ritual phenomenon in the Central Andes during the Late Archaic to Formative periods. Characterized by ceremonial structures featuring central hearths, ventilated chambers, and plastered walls, this tradition played a fundamental role in the development of socio-religious complexity across the region. Despite decades of research, significant debates persist regarding its chronological development and cultural dynamics (Elizabeth Bonnier, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1983\u003c/span\u003e; Elisabeth Bonnier, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1988\u003c/span\u003e; Elizabeth Bonnier, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; R. L. Burger \u0026amp; Salazar-Burger, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e; Mesia-Montenegro \u0026amp; Sanchez-Borjas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCurrent scholarship presents conflicting interpretations of the KRT's origins, with some researchers advocating for independent development in the highlands at sites like Kotosh and Huaricoto (R. Burger \u0026amp; Salazar, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; R. L. Burger \u0026amp; Salazar-Burger, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e), while others propose unidirectional diffusion from coastal centers such as Huaricanga or Caral (Creamer, Ruiz, Perales, \u0026amp; Haas, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Piscitelli, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2017a\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2017b\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThese contrasting perspectives stem from persistent challenges in the archaeological record. Ambiguities in temporal overlap between coastal and highland ritual practices, biases in site representation due to stratigraphic gaps and uneven sampling, and the absence of high-precision chronological frameworks have hindered evaluations of cultural hybridity, bidirectional exchange, or ideological movement. These limitations have prevented consensus on the KRT's spatial and temporal trajectory and its role in pan-Andean ideological networks.\u003c/p\u003e \u003cp\u003eTo resolve these inconsistencies, this study addresses three fundamental questions: First, what were the chronological origins and dissemination pathways of the KRT? Second, how did temporal overlaps between early coastal monumental complexes and highland ritual practices inform patterns of cultural coexistence or ideological change? Third, can we identify evidence for multidirectional cultural transmission that challenges linear diffusion theories?\u003c/p\u003e \u003cp\u003eI address these questions through Bayesian chronological analysis of 168 radiocarbon dates from 16 Late Archaic and Formative period sites across Peru's central coast and highlands. This approach aims to establish a unified high-precision timeline that clarifies the KRT's developmental trajectory while providing a framework to assess environmental, political, and religious drivers of social change in early Andean societies.\u003c/p\u003e \u003cp\u003eThe Late Archaic and Formative Periods\u003c/p\u003e \u003cp\u003eThe Late Archaic (ca. 3500\u0026ndash;1800 cal BCE) in the Central Andes witnessed a dramatic escalation of socio-political complexity that preceded the technological hallmarks traditionally used to mark the ensuing Formative. Coastal centers such as Caral and Huaricanga erected extensive platform mounds, circular sunken plazas, and terraced pyramids in the complete absence of ceramics or loom-woven textiles, overturning the premise that sophisticated craft production is a prerequisite for monumentality (Hass \u0026amp; Creamer, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Ruth Shady, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). These initiatives were sustained by a diversified economy that braided maritime exploitation, floodplain agriculture, and highland foraging, fostering population growth and long-distance exchange (Pozorski \u0026amp; Pozorski, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). While coastal sites invested in large, communal architectural programs that anchored emerging elites, highland settlements such as Huaricoto and Piruru expressed the same ideological repertoire through more modest, hearth-centered shrines linked to the Kotosh Religious Tradition (Elizabeth Bonnier, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; R. L. Burger \u0026amp; Salazar-Burger, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe coexistence of aceramic monumentality with unambiguous evidence of social stratification complicates long-standing periodization. Steward\u0026rsquo;s initial definition of the \u0026ldquo;Formative\u0026rdquo; rested on ceramics, mound\u0026ndash;temple\u0026ndash;priest complexes, and intensified agriculture (Steward, \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e1948\u003c/span\u003e; Willey \u0026amp; Phillips, \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e1958\u003c/span\u003e) subsequently foregrounded maize\u0026ndash;manioc farming and sedentary village life. Yet the Late Archaic record reveals \u0026ldquo;Formative-like\u0026rdquo; political integration without pottery, highlighting the risk of reifying technological thresholds into universal cultural stages (D. A. Contreras, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Watanabe, \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe conventional Formative (ca. 2200\u0026ndash;200 cal BCE) is marked archaeologically by the introduction of ceramics, early metallurgy, and loom textiles\u0026mdash;innovations often credited with propelling irrigation expansion, demographic packing, and settlement diversification (Lumbreras, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1989\u003c/span\u003e). Technological determinism, however, obscures the Late Archaic\u0026rsquo;s demonstrable capacity to generate complex institutions through non-material pathways, including integrative religion, nascent administration, and sophisticated resource management (Feldman, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Hass \u0026amp; Creamer, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Recent Bayesian modelling of radiocarbon sequences refines absolute chronologies and shows that ceramics frequently appear centuries after the consolidation of monumental architecture, suggesting that craft technologies amplified rather than initiated socio-political transformations.\u003c/p\u003e \u003cp\u003eMonumentality throughout both periods served a dual mandate: as a stage for collective religious performance that forged supra-household cohesion, and as an instrument through which emergent elites materialized authority (Kembel \u0026amp; Rick, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Rick, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). The continuity of architectural canons across the Late Archaic\u0026ndash;Formative divide indicates that ideological commitments, not simply technological advances, underpinned Andean pathways to complexity.\u003c/p\u003e \u003cp\u003eTaken together, the Late Archaic and Formative are best viewed as overlapping processes. The former demonstrates that monumental construction, ritual centralization, and hierarchical leadership could flourish independent of ceramic or textile technologies; the latter documents how subsequent innovations intensified and diversified these foundations. This Andean trajectory underscores the need for analytical frameworks that integrate ecology, economy, religion, and politics alongside material proxies, and it endorses Bayesian chronologies as a critical tool for disentangling the asynchronous cadence of technological and institutional change.\u003c/p\u003e \u003cp\u003eThe Kotosh Religious Tradition\u003c/p\u003e \u003cp\u003eThe KRT, named after the eponymous highland site of Kotosh near Hu\u0026aacute;nuco, in the Andean central highlands, constitutes one of the earliest architecturally formalized ritual systems in the Central Andes. Active from the Late Archaic into the Formative, the KRT is defined by fire-focused ceremonies conducted within freestanding buildings that center on stone-lined hearths used for the controlled burning of offerings. Walls were plastered, floors stepped or split-level, and interior niches framed ritual paraphernalia (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e01\u003c/span\u003e), marking these spaces as dedicated cult facilities rather than domestic dwellings (R. Burger \u0026amp; Salazar, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1980\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; R. L. Burger \u0026amp; Salazar-Burger, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAlthough a shared architectural structure united KRT communities, its expression varied with environment. On the hyper-arid central coast, settlements such as Caral and Huaricanga embedded KRT elements\u0026mdash;central hearths, axial ventilation shafts, cyclic renovation\u0026mdash;into monumental complexes of terraces and sunken plazas capable of hosting large congregations (Piscitelli, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2017b\u003c/span\u003e; Ruth Shady, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Ruth Shady, Haas, \u0026amp; Creamer, \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Highland centers such as Huaricoto and Piruru instead favored smaller, enclosed temples in which hearths facilitated more intimate ceremonies (Elizabeth Bonnier, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1983\u003c/span\u003e; Elisabeth Bonnier, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1988\u003c/span\u003e; R. Burger \u0026amp; Salazar, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1980\u003c/span\u003e). Regardless of scale, the recurrent dismantling, rebuilding, and deliberate burial of hearths articulated a doctrine of cyclical renewal and ancestral veneration. Each reconstruction materialized continuity, rooting contemporary ritual practice in a storied past.\u003c/p\u003e \u003cp\u003eThe sociopolitical reach of the KRT was as consequential as its religious program. By concentrating priestly authority around publicly visible hearth rituals, temple precincts forged communal identity while legitimizing emerging leaders who choreographed the ceremonies and controlled access to sacred fire. This \u0026ldquo;embedded religiousness\u0026rdquo; (Mesia-Montenegro \u0026amp; Sanchez-Borjas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u0026mdash;the inseparability of cult practice and political power\u0026mdash;became a hallmark of later Andean polities, which likewise fused religious and administrative roles within monumental architecture.\u003c/p\u003e \u003cp\u003eGeography and space\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eTo date, twenty-three archaeological sites exhibiting KRT structures have been identified across the Central Andes, distributed over an estimated area of 80,000 km\u0026sup2; (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Of these, sixteen sites (70%) have been dated, with the highest concentration observed in the Ancash region (nine sites) and Hu\u0026aacute;nuco (four sites). Southern occurrences are documented in Lima (two sites), while northern examples are in Cajamarca (two sites).\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eKRT sites demonstrate significant environmental variability, occupying distinct ecological zones: Coastal zones proximal to the littoral (e.g., Huaynun\u0026aacute;, Bah\u0026iacute;a Seca, Gramalote, Macabalaca, El Para\u0026iacute;so, Alto Salaverry). Intermediate coastal valleys (e.g., Taukachi-Konk\u0026aacute;n, Pampa de las Llamas, Caral, Huaricanga, Buenavista). Eastern humid montane regions (e.g., Shillacoto, Piruru, Wairajirca, Kotosh) and Highland zones (e.g., La Seductora, La Galgada, El Silencio, Hualcay\u0026aacute;n, Acshicupoto, Huaricoto, Chav\u0026iacute;n de Hu\u0026aacute;ntar).\u003c/p\u003e \u003cp\u003eThis environmental diversity is reflected in the archaeological record, where KRT structures manifest in three primary contextual configurations: Autonomous architectural features (e.g., La Seductora, Huaricoto, Piruru). Central elements within complex architectural layouts (e.g., Kotosh, La Galgada, Caral, Acshicupoto). Peripheral components associated with large-scale architectural complexes (e.g., Huaricanga, Pampa de las Llamas, Taukachi-Konk\u0026aacute;n, Huaricanga, Chav\u0026iacute;n de Hu\u0026aacute;ntar).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe variability observed in site placement and structural integration points to the adaptive strategies and sociocultural dynamics of prehispanic populations participating in the KRT tradition. Readers seeking site overviews and specifics should consult SI01.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eTo establish a robust absolute chronology for the KRT cultural complex, this study integrates 168 radiocarbon dates from associated archaeological sites (SI02). This study applies Bayesian chronological modeling in OxCal v.4.4.4, following strict radiocarbon calibration and statistical protocols (Bronk-Ramsey, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Napolitano et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This approach addresses critical challenges in evaluating site contemporaneity, temporal overlap, and regional occupation patterns while systematically quantifying uncertainties inherent to radiocarbon datasets.\u003c/p\u003e \u003cp\u003eBayesian methods provide a statistically robust framework for synthesizing prior archaeological knowledge with radiocarbon likelihoods, thereby refining posterior age estimates beyond conventional calibration (Bronk-Ramsey, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Dye, Buck, DiNapoli, \u0026amp; Philippe, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Following established workflows (Brown, Anderson, Junge, \u0026amp; Duelks, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Hamilton \u0026amp; Krus, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Manning \u0026amp; Hart, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Sghinolfi, Millaire, \u0026amp; Roy, \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), I structured models to treat each site as an independent Sequence within a hierarchical regional Phase, avoiding assumptions of temporal ordering. Site-specific boundaries were defined to reflect chronological breaks or transitions, with Markov Chain Monte Carlo (MCMC) sampling generating posterior distributions that integrate measurement errors and calibration curves. This methodology advances precision by formalizing uncertainty propagation, particularly for datasets with overlapping or sparse date ranges (Dye et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo evaluate occupation dynamics across the study area, I implemented OxCal v.4.4.4\u0026rsquo;s Difference and Order (OCT) functions (Bronk Ramsey, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). By applying the Difference Command to compare initiation/termination boundaries between sites, I quantified intervals of potential overlap or hiatus (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and SI03), while OCT tested hypotheses of sequential occupation (SI04) (e.g., Site A preceding Site B) (S5) (Brown et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Manning \u0026amp; Hart, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Sghinolfi et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This method avoids a \u003cem\u003epriori\u003c/em\u003e assumptions of cultural or temporal continuity, instead allowing the data to probabilistically define regional patterns.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSite chronologies are defined by their Start and End Boundaries (95.4% confidence intervals), derived from Bayesian posterior distributions. These boundaries represent the most probable temporal spans of occupation. Full tabulated results, including posterior density estimates, specifications, and diagnostic outputs are archived in SI05 to facilitate replication and reuse.\u003c/p\u003e \u003cp\u003eThis approach advances reproducibility in chronology-building by formalizing probabilistic tests of temporal hypotheses, a critical step for regional syntheses in archaeology (Dye et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eChronological Hygiene\u003c/p\u003e \u003cp\u003eCurrent chronological frameworks in the study region exhibit a historical bias toward monumental sites, leading to systematic underrepresentation of smaller settlements in temporal reconstructions. Addressing this imbalance necessitates a dual focus in future research: (1) expanding radiocarbon datasets to incorporate underrepresented sites and (2) improving chronometric precision through adherence to modern sampling protocols (e.g., short-lived organic materials, stratigraphically secure contexts).\u003c/p\u003e \u003cp\u003eAll radiocarbon dates (168) were compiled from published literature (S02) and assessed using a four-tier chronological hygiene framework (Kidder \u0026amp; Grooms, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), which categorizes dates from rank 1 (highest reliability: e.g., short-lived taxa, secure stratigraphic association) to rank 4 (lowest: e.g., long-lived wood, uncertain provenance). This system, adapted from Napolitano et al. (Napolitano et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) and Krus (Krus, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), enables transparent prioritization of chronometric data (see S02, \u0026ldquo;CH\u0026rdquo; column for criteria).\u003c/p\u003e \u003cp\u003eCalibration was conducted in OxCal v.4.4.4 with the SHCal13 curve (Hogg et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), the established standard for southern hemisphere regions (Marsh et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Although Nesbitt et al. (Nesbitt, Asencios, \u0026amp; Tokanai, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) report minimal divergence between SHCal13, IntCal13, and mixed curves at Andean highland sites (e.g., Reparin), SHCal13 was uniformly applied across coastal and highland contexts to ensure methodological consistency. This approach facilitates direct comparability with regional studies while maintaining transparency. The model\u0026rsquo;s modular construction permits iterative updates as new calibration curves or data become available\u0026mdash;a flexibility validated through prior applications to Andean coastal U-shaped structures (Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Such adaptability supports open science objectives, enabling future revisions without compromising reproducibility or regional applicability.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eChronological hygiene levels (based on Kidder and Grooms, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevel 01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAccurate dating requires the sample to come from a context that reliably dates the deposit, with sufficient information to link the sample's death to context formation. The dating must include detailed reporting, provenience information, and the laboratory's identification.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevel 02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe dates rely on single-entity charcoal, charred material, or marine/freshwater shells not identified to taxon. Understanding of reservoir effects is partial, and evidence of deposition during context use is limited or unclear. The dating process must include detailed sample reporting, provenience information, and the processing laboratory's name and reference number.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevel 03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe dates are based on unidentified single-entity charcoal, charred material, or marine/freshwater shells, with little to no understanding of reservoir effects. They may include radiometric dates on human bone apatite or samples that likely predate their recovery context, modeled as terminus post quem. These dates may also have incomplete or unclear contextual information.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevel 04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe dates are based on multi-entity samples, like mixed charcoal, shells from multiple individuals, or bulk sediment, with unclear or compromised contextual relationships. This also includes cases where the material type is unspecified, the sample is contaminated, or fractionation corrections were not applied, especially for samples from maize, cane, or aquatic organisms\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\u003cp\u003eFollowing Conolly\u0026rsquo;s guidelines (Connolly, \u003cspan class=\"CitationRef\"\u003e2006\u003c/span\u003e), any determination with a laboratory standard deviation greater than 90 years was discarded. I then applied the \u0026ldquo;chronological hygiene\u0026rdquo; (CH) scale, retaining only ranks 1\u0026ndash;2. Together, these filters removed 62 of 168 determinations (37%), most of them from Huaricoto, Kotosh, Bah\u0026iacute;a Seca and Huacaloma, whose dates are imprecise. The resulting datasets underpin four alternative models (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e02\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 02\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBayesian models produced by OxCal according to their chronological hygiene standards and A model and overall values.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModel A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModel B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModel C\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eModel D\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAll dates\u003c/p\u003e \u003cp\u003e168 dates\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eσ\u0026thinsp;\u0026le;\u0026thinsp;90 yr\u003c/p\u003e \u003cp\u003e141 dates\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDates ranked 1 and 2.\u003c/p\u003e \u003cp\u003e106 dates\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDates ranked 1 and 2.\u003c/p\u003e \u003cp\u003eσ\u0026thinsp;\u0026le;\u0026thinsp;90 yr\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA model, 58.9. A overall,68.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA model, 32.0 A overall, 44.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eA model, 88.8. A overall, 84.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA model, 85.4. A overall 86.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBayesian Modelling and Kernel Density Estimation\u003c/p\u003e \u003cp\u003eBayesian Chronological Modelling\u003c/p\u003e \u003cp\u003eFour independent phased models were constructed, treating each archaeological site as a distinct \u003cem\u003eSequence\u003c/em\u003e within hierarchical regional \u003cem\u003ePhases\u003c/em\u003e. This approach intentionally avoided imposing temporal ordering assumptions. Site initiation and termination boundaries were calculated using OxCal's Boundary function, which generates probability distributions for start and end dates at 95.4% confidence intervals through Markov Chain Monte Carlo (MCMC) sampling. This method integrates measurement errors, and calibration curve uncertainties to produce robust temporal ranges, preserving full probabilistic distributions rather than relying on simplified point estimates like medians (Bronk Ramsey \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eModel Validation, Agreement Index and Outliers\u003c/p\u003e \u003cp\u003eModel reliability was assessed using OxCal's Agreement Index (A-index). I required models to meet dual thresholds: an \u003cem\u003eA_model\u003c/em\u003e value\u0026thinsp;\u0026ge;\u0026thinsp;60% indicating element-level coherence with prior constraints, and an \u003cem\u003eA_overall\u003c/em\u003e value\u0026thinsp;\u0026ge;\u0026thinsp;60% confirming global structural validity (Hamilton \u0026amp; Krus, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ramsey, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1995\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Models failing these thresholds (e.g., Model B: \u003cem\u003eA_overall\u003c/em\u003e\u0026thinsp;=\u0026thinsp;44%) were rejected. Both indices must exceed a threshold of \u0026ge;\u0026thinsp;60% to indicate robust agreement between the input data and modeled chronology. To ensure the reliability of Bayesian chronometric models in OxCal, it is essential to validate their statistical coherence using the A model and A overall model metrics.\u003c/p\u003e \u003cp\u003eWhen constructing a Bayesian radiocarbon sequence, it is unrealistic to treat every determination as perfect. Laboratory uncertainty, residual contaminants, and stratigraphic mixing all produce occasional dates that diverge markedly from true age. To recognize this empirical reality the model employs OxCal\u0026rsquo;s general outlier framework, Outlier Model (\"General\", T(5), U(0.4), \"t\"). The Student-t kernel with five degrees of freedom supplies heavy tails, permitting sizeable deviations to be absorbed without dragging the entire sequence; in effect, most determinations behave as if Gaussian, but genuine outliers are granted the statistical room they require. The accompanying uniform prior U(0, 0.4) stipulates a conservative 0\u0026ndash;40% chance that any single result is abnormal. This retains confidence that most dates are sound while allowing as many as two in five to be down-weighted if the likelihood function demands it.\u003c/p\u003e \u003cp\u003eApplying the outlier tag \u0026ldquo;t\u0026rdquo; imposes uniform criteria, eliminating subjective exclusions and post-hoc adjustments. Consequently, the final chronology internalizes both the shared structure of the dataset and an explicit skepticism toward outliers, yielding phase boundaries that are more robust, transparent, and reproducible.\u003c/p\u003e \u003cp\u003eKernel Density Estimation Implementation\u003c/p\u003e \u003cp\u003eI applied Kernel Density Estimation (KDE) to site-level posterior distributions using OxCal's KDE_Plot function (Bronk-Ramsey, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This approach enhances interpretability of occupation phases (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e04\u003c/span\u003e) while addressing known limitations of summed probability distributions (SPDs), where calibration curve irregularities and sampling biases generate artificial peaks (D. A. Contreras \u0026amp; Meadows, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Michczynski \u0026amp; Michczynska, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). KDE smoothing reduces noise from calibration artifacts (Bayliss, Ramsey, Van der Plicht, \u0026amp; Whittle, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) and mitigates distortions from uneven temporal sampling (Chiverrell, Thorndycraft, \u0026amp; Hoffmann, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), clarifying genuine trends while suppressing spurious fluctuations.\u003c/p\u003e \u003cp\u003eI selected KDE_Plot over KDE_Model for its non-intrusive visualization of existing Bayesian outputs. Unlike KDE_Model\u0026mdash;which constructs independent probability distributions risking over-parametrization\u0026mdash;KDE_Plot preserves the integrity of our phased models while enhancing trend clarity. This approach maintains contextual fidelity and chronological hygiene protocols without introducing redundant assumptions. Full model specifications and reproducible code are in SI06.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSummed Probability Limitations\u003c/p\u003e \u003cp\u003eWhile Summed Probability Distribution (SPDs) are commonly used as demographic proxies, I recognize their constraints: they primarily reflect research intensity rather than past population dynamics (Contreras \u0026amp; Meadows \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), and calibration artifacts can artificially amplify certain periods (Michczyński \u0026amp; Michczyńska 2006). My phased KDE approach counters these issues by focusing on relative phase durations rather than absolute probability values, prioritizing chronological relationships over demographic inference. My priority is establishing robust chronological relationships (when phases start/end relative to each other) rather than making direct demographic inferences (how big the population was).\u003c/p\u003e \u003cp\u003ePhase Delimitation\u003c/p\u003e \u003cp\u003eTo reconstruct the chronology of sites, I first employed the OxCal \u0026ldquo;Order\u0026rdquo; (OCT) matrix to evaluate pairwise start\u0026ndash;start and end\u0026ndash;end probabilities. By counting, for each site A, the number of other sites B for which P(Start A\u0026thinsp;\u0026lt;\u0026thinsp;Start B)\u0026thinsp;\u0026gt;\u0026thinsp;0.50\u0026mdash;and analogously for end boundaries\u0026mdash;I derived a ranked sequence of site foundations (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e03\u003c/span\u003e) (R code in SI07).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 03\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003ea.\u003c/b\u003e Model A. Ranked sequence of site foundations.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRank\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEvent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSum Prob\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huaricanga\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16.4096\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huaricoto\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16.132\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Pampa\u0026nbsp;de\u0026nbsp;las\u0026nbsp;Llamas\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.9996\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Acshicupoto\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12.921998\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huaynuna\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.659698\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e6\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;La\u0026nbsp;Galgada\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.871596\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e7\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Piruru\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.771917\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Caral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.286102\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Hualcayan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.901971\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Kotosh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8.841999\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e11\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Buenavista\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.952022\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e12\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;El\u0026nbsp;Paraiso\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.417186\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e13\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Shillacoto\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.487267\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e14\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Taukachi-Konkan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.623591\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e15\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Bahia\u0026nbsp;Seca\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.168294\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e16\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Gramalote\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.535116\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e17\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huacaloma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.983\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e18\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Chavin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0371\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 03\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eb.\u003c/b\u003e Model D. Ranked sequence of site foundations.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRank\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEvent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSum Prob\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huaricanga\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.8548\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Pampa\u0026nbsp;de\u0026nbsp;las\u0026nbsp;Llamas\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.92815\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Acshicupoto\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.17235\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Huaynuna\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.998738\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;La\u0026nbsp;Galgada\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.273515\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e6\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Piruru\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.202276\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e7\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Caral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.727266\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Hualcayan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.439196\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Buenavista\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.08595\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;El\u0026nbsp;Paraiso\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.986617\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e11\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Taukachi-Konkan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.821638\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e12\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Gramalote\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.492781\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e13\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStart\u0026nbsp;Chavin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.01684\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eNext, to delineate discrete chronological phases within this sequence, I extracted the 95.4% highest-posterior‐density (HPD) intervals for every phase boundary (both start and end) from the OxCal outputs (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e05\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo capture the uncertainty more accurately in my chronology of the KRT, I implemented a Monte Carlo\u0026ndash;based kernel density estimation (KDE) of phase-breaks. Rather than collapsing each site\u0026rsquo;s calibrated radiocarbon HPD (highest posterior density) interval to a single midpoint, I repeatedly sampled one date from each interval and used those random draws to build a KDE of boundary density. By drawing uniformly from every Lower95.4\u0026ndash;Upper95.4 bound and aggregating across sites, each individual KDE run represents one plausible realization of when cultural transitions occurred.\u003c/p\u003e \u003cp\u003eI conducted ten thousand such replications, each time fitting a continuous density estimate (with a 100-year bandwidth) and extracting its first five local minima\u0026mdash;the troughs that correspond to the boundaries between successive phases. Collecting these minima across all runs yields a distribution for each phase-break. I summarize each trough\u0026rsquo;s distribution by its median date and the 2.5\u0026ndash;97.5% quantile interval. In Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e06\u003c/span\u003e, the bold black curve is the median KDE; the surrounding gray ribbon marks the 95% envelope of all simulations; and the dashed vertical lines show the five median phase-break dates. For Model A, the Montecarlo KDE analysis revealed five pronounced troughs at approximately 3138, 2641, 2155, 1664 and 1180 cal BCE. For Model D, the R-based KDE analysis revealed five pronounced troughs at approximately 3011, 2414, 1842, 1305 and 1100 cal BCE (SI08)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis approach\u0026mdash;combining OxCal ordering, interval midpoints and Montecarlo kernel-density smoothing\u0026mdash;provides a straightforward, reproducible workflow for defining discrete phases in poorly dated regions. The resulting phased chronology underpins our interpretation of the Kotosh Religious Tradition\u0026rsquo;s emergence, growth, consolidation, and decline.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eRadiocarbon Analysis\u003c/p\u003e \u003cp\u003eFollowing accurate evaluation of Bayesian chronological models, the analysis was focused on Models A and D due to their superior statistical coherence and reliability. Model A yielded agreement indices, with an A model value of 58.9 and an A overall value of 68.4, while Model D demonstrated concordance, achieving an A model of 85.4 and A overall of 86.9. In contrast, Model B, despite employing radiocarbon dates with tighter measurement uncertainties (σ), produced critically low agreement indices (A model\u0026thinsp;=\u0026thinsp;32; A overall\u0026thinsp;=\u0026thinsp;44), rendering it statistically unreliable for robust chronological inference. Although Model C exhibited an acceptable agreement (A model\u0026thinsp;=\u0026thinsp;88.8; A overall\u0026thinsp;=\u0026thinsp;84.7), its chronological hygiene standards were surpassed by the Caral model, which also achieved higher A model values (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). While the A value for Model A is (58.9) falls slightly below the conventional 60% threshold, its selection is justified by the model\u0026rsquo;s strong overall agreement (A overall\u0026thinsp;=\u0026thinsp;68.4). Sensitivity analysis confirmed that removing this sample did not significantly alter the phase boundaries, supporting its retention.\u003c/p\u003e \u003cp\u003eThis selective focus Models A and D is justified by their adherence to stringent chronometric protocols, which are critical for high-resolution temporal reconstructions in Andean archaeology.\u003c/p\u003e \u003cp\u003eWhile dataset reduction introduces trade-offs in sample size, this aligns with best practices for chronological hygiene (Kidder \u0026amp; Grooms, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Napolitano et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), emphasizing precision in occupation-phase modeling.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eWhile summarizing the findings of models A and D, in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e4\u003c/span\u003e and providing all the data as supplementary information for scholars to review and compare interpretations, I will focus on examining Models A and D in the following sections. The visualization details for both models and their interactions can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e07\u003c/span\u003e.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 04\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003ea\u003c/b\u003e. Model A, stages, and phases\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStages\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYears BC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSites\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDecline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1200\u0026ndash;300 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuacaloma, Piruru, Chav\u0026iacute;n, Huaricoto\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eConsolidation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1700\u0026thinsp;\u0026minus;\u0026thinsp;1200 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePiruru, Hualcay\u0026aacute;n, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Bah\u0026iacute;a Seca, Taukachi-Konk\u0026aacute;n, Huacaloma, Gramalote\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2200\u0026thinsp;\u0026minus;\u0026thinsp;1700 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricoto, Huaynun\u0026aacute;, Piruru, Hulcay\u0026aacute;n, Caral, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eExpansion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2600\u0026thinsp;\u0026minus;\u0026thinsp;2200 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricanga, Huaricoto, Pampa de las Llamas, Acshicupoto, Huaynun\u0026aacute;, La Galgada, Piruru, Caral, Hualcay\u0026aacute;n, Kotosh\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3100\u0026thinsp;\u0026minus;\u0026thinsp;2600 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricanga, Huaricoto, Pampa de las Llamas, Acshicupoto, Huaynun\u0026aacute;, La Galgada\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOnset\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3600\u0026thinsp;\u0026minus;\u0026thinsp;3100 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricanga and Huaricoto\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eb.\u003c/b\u003e Model D, stages, and phases\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStages\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYears BC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSites\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDecline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1100\u0026ndash;500 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eChavin\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eConsolidation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1300\u0026thinsp;\u0026minus;\u0026thinsp;1100 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePiruru, Hualcay\u0026aacute;n, Pampa de las Llamas, El Para\u0026iacute;so, Gramalote\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1800\u0026thinsp;\u0026minus;\u0026thinsp;1300 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaynun\u0026aacute;, Piruru, Hualcay\u0026aacute;n, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Taukachi-Konk\u0026aacute;n, Gramalote\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eExpansion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2400\u0026thinsp;\u0026minus;\u0026thinsp;1800 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eHuaricanga, Huaynun\u0026aacute;, Piruru, Hualcay\u0026aacute;n, Pampa de las Llamas, Caral, La Galgada, Buenavista\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3000\u0026thinsp;\u0026minus;\u0026thinsp;2400 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricanga, Pampa de las Llamas, Huaynun\u0026aacute;, Piruru, Acshicupoto and Caral\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOnset\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3600\u0026thinsp;\u0026minus;\u0026thinsp;3000 BCE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhase 01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHuaricanga\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eModel A\u003c/p\u003e \u003cp\u003eAs previously stated, this model encompasses the complete dataset. The A-Model\u0026rsquo;s values are 58.9 and 68.4. As explained before, the statistics for A values render the model acceptable (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e08\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eOnset Stage (3600\u0026thinsp;\u0026minus;\u0026thinsp;3100 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is represented by the emergence of early KRT structures across the Central Andes.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePhase 01 (3600 − 3100 BCE)\u003c/h3\u003e\n\u003cp\u003eOnly two ceremonial centers fall within the earliest span of the Kotosh Religious Tradition: Huaricanga on the lower Fortaleza-Supe divide and Huaricoto in the upper Santa (Ancash) drainage.\u003c/p\u003e \u003cp\u003eArchitecturally, the two sites contrast sharply. Huaricanga comprises multiple KRT rooms arranged beside large platform buildings and circular sunken courts, attesting to substantial labour mobilisation and sophisticated planning. Huaricoto, by comparison, is smaller and its KRT rooms lack the massive stone walling seen on the coast. The greater investment evident at Huaricanga implies stronger managerial capacities and more reliable access to construction resources, signalling an early concentration of ritual authority in the lower valleys. Together, these two centers mark the initial appearance of KRT architectural and ideological motifs in both coastal and highland settings, laying the foundations for the subsequent expansion documented in later phases.\u003c/p\u003e\n\u003ch3\u003eExpansion Stage (3100 − 2600 BCE)\u003c/h3\u003e\n\u003cp\u003eThis stage is represented by the expansion of KRT structures into the coast, highlands, and Andean mountains.\u003c/p\u003e\n\u003ch3\u003ePhase 02 (3100 − 2600 BCE)\u003c/h3\u003e\n\u003cp\u003eDuring this interval, seven contemporaneous centers sustained KRT ritual activity: the long-occupied sites of Huaricanga and Huaricoto; the coastal enclave of Pampa de las Llamas; the littoral complex of Huaynun\u0026aacute;; two newly founded high‐altitude sites at Acshicupoto and La Galgada (Ancash).\u003c/p\u003e \u003cp\u003eThe material record reveals a pronounced territorial expansion. Along the central coast, Pampa de las Llamas and Huaynun\u0026aacute; extend the KRT into littoral settings; concurrently, in the Cordillera Negra, the founding of Acshicupoto and La Galgada attests to the tradition\u0026rsquo;s sustained penetration into Ancash highlands. La Galgada, surpasses the earlier highland site at Huaricoto in both scale and elaboration, signaling the ascendant prestige of KRT ceremonialism beyond the coast.\u003c/p\u003e\n\u003ch3\u003ePhase 03 (2600 − 2200 BCE)\u003c/h3\u003e\n\u003cp\u003eThere are ten centers within this 400-year span: Huaricanga, Huaricoto and Pampa de las Llamas; Acshicupoto, Huaynun\u0026aacute;, La Galgada and Piruru; and three newcomers\u0026mdash;Caral, Hualcay\u0026aacute;n and Kotosh.\u003c/p\u003e \u003cp\u003eArchaeologically, Phase 03 extends the spatial growth documented in Phase 02 but introduces markedly more elaborate ceremonial architecture. Caral\u0026rsquo;s monumental platform mounds, Hualcay\u0026aacute;n\u0026rsquo;s terraces and Kotosh\u0026rsquo;s sculpted temples all signal a step-change in construction scale and ritual complexity. Their near-synchronous emergence across distinct ecological zones\u0026mdash;lower Supe valley, high Callej\u0026oacute;n de Huaylas and upland Hu\u0026aacute;nuco\u0026mdash;suggests intensified interregional communication and the consolidation of shared canons. Phase 03 blends long-standing coastal sites with new monumental highland counterparts into an increasingly integrated ceremonial sphere.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eConsolidation (2200\u0026thinsp;\u0026minus;\u0026thinsp;1200 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is represented by the expansion of KRT structures into the coast, highlands, and Andean mountains.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePhase 04 (2200 − 1700 BCE)\u003c/h3\u003e\n\u003cp\u003eDuring this interval, ten centers maintained almost synchronous ritual activities, Huaricoto, Huaynun\u0026aacute;, Piruru, Hualcay\u0026aacute;n, Caral, Kotosh, La Galgada, Pampa de las Llamas, Buenavista and El Paraiso. The integration of KRT elements into the U-shaped complex at El Para\u0026iacute;so exemplifies the transmission of ritual norms into densely settled coastal zones, marking a critical shift from a highland-confined phenomenon to an interregional ceremonial network. This phase of consolidation coincides with paleoclimatic proxies indicating heightened ENSO variability (Caramanica, Quilter, Huaman, Villanueva, \u0026amp; Morales, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), suggesting that episodic climate perturbations fostered supra-local cooperation.\u003c/p\u003e\n\u003ch3\u003ePhase 05 (1700 − 1200 BCE)\u003c/h3\u003e\n\u003cp\u003eRadiocarbon results indicate that eleven centers remained active during this interval: Piruru, Hualcay\u0026aacute;n, Kotosh, La Galgada, Pampa de las Llamas, Buenavista, El Paraiso, Bah\u0026iacute;a Seca, Taukachi-Konk\u0026aacute;n, Huacaloma and Gramalote.\u003c/p\u003e \u003cp\u003eThis phase represents the moment at which KRT ceremonialism achieved maximal geographic integration\u0026mdash;establishing a unified ritual repertoire across both the Andean highlands and the central\u0026ndash;north coast and laying the ideological groundwork for the tradition\u0026rsquo;s subsequent pan-Andean expansion. Coastal nodes such as Pampa de las Llamas and El Para\u0026iacute;so sustained large-scale construction and communal ritual activities, demonstrating persistent administrative capacity. In the highlands, the emergence of Huacaloma attests to the continued resonance of KRT ideology and its northward dissemination into Cajamarca.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDecline Stage (1200\u0026thinsp;\u0026minus;\u0026thinsp;300 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is characterized by the substantial reduction of KRT sites in the Andes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePhase 06 (1200\u0026thinsp;\u0026minus;\u0026thinsp;300 BCE)\u003c/h2\u003e \u003cp\u003eBy Phase 06, the KRT enters a period of contraction and transformation. Only a handful of core centers\u0026mdash;most notably Huacaloma, Piruru, Huaricoto, and Chav\u0026iacute;n\u0026mdash;continue with the KRT. Across the broader landscape, KRT is repurposed or abandoned.\u003c/p\u003e \u003cp\u003eAcross the Central Andes, the widespread abandonment of U-shaped temple complexes and the political contraction of Chav\u0026iacute;n de Hu\u0026aacute;ntar (Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) mark the terminal dissolution of KRT as an interregional phenomenon. At Chav\u0026iacute;n, KRT architectural elements are confined to peripheral courts, indicating that KRT assumed a subordinate position within an increasingly pluralistic religious milieu. This interval coincides with an intensified ENSO (D. Sandweiss, Shady, Moseley, Keefer, \u0026amp; Ortloff, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; D. H. Sandweiss et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) and a major Ancash earthquake ca. 550 BCE events that destabilized agrarian production and eroded coastal elites\u0026rsquo; capacity for mobilizing large labor forces.\u003c/p\u003e \u003cp\u003eStable-isotope analyses from human and faunal remains in the Supe Valley indicate that, after ca. 500 BCE, climatic variability and agrarian stress precipitated sociopolitical instability: collapsing crop yields, escalating competition for resources, and eroded elite capacity to sustain centralized governance (Pezo-Lanfranco et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). This period of destabilization coincides also with the decline of Chav\u0026iacute;n de Hu\u0026aacute;ntar\u0026rsquo;s pan-Andean influence (Rick, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Rick et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Kotosh Model reveals a dynamic trajectory characterized by spatial expansion, architectural innovation, and cultural integration. Rigorous chronological and analytical methods (including OCT and Difference Command analyses) underpin the identification of sequential patterns in site emergence, expansion, consolidation, and decline. The evolution of the KRT\u0026mdash;from its early ceremonial centers to its eventual integration and regional diversification\u0026mdash;reflects complex interactions among environmental, social, and ideological factors over three millennia.\u003c/p\u003e \u003cp\u003eModel D\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAs previously noted, this model analyzes dates classified under chronological hygiene levels 1\u0026ndash;2, excluding those with standard deviations exceeding ninety. With A model values of 95.9 and 95.0 \u0026mdash;surpassing the 60-threshold required for acceptability, it demonstrates robust performance. Furthermore, this model achieves the highest A-model value among all four models produced, solidifying its position as the most statistically reliable version (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e09\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eOnset Stage (3600\u0026thinsp;\u0026minus;\u0026thinsp;3000 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is represented by the emergence of early KRT structures across the Central Andes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003ePhase 01 (3600\u0026thinsp;\u0026minus;\u0026thinsp;3000 BCE)\u003c/h2\u003e \u003cp\u003eThis initial phase is demarcated by Huaricanga, located in the mid-Pativilca Valley, situated in the north-central Andean coast. As mentioned before, at Huaricanga, KRT structures were not placed in a prominent position but next to larger mounds and circular sunken courts.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eExpansion Stage (3000\u0026thinsp;\u0026minus;\u0026thinsp;1800 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is represented by the expansion of KRT structures into the coast and highlands.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003ePhase 02 (3000\u0026thinsp;\u0026minus;\u0026thinsp;2400 BCE)\u003c/h2\u003e \u003cp\u003eThis phase marks the KRT\u0026rsquo;s first coastal\u0026ndash;highland expansion. North-coastal Huaynun\u0026aacute; and south-coastal Caral adopt canonical rectangular temples with central hearths and wall niches, while Acshicupoto carries the tradition upslope, signaling emergent inter-valley networks. Yet coastal centers retain distinctive local character: at Caral, KRT temples dominate the settlement core, whereas at Huaricanga they remain subsidiary outbuildings flanking larger mounds and sunken-court complexes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003ePhase 03 (2400\u0026thinsp;\u0026minus;\u0026thinsp;1800 BCE)\u003c/h2\u003e \u003cp\u003eThis period marks a critical point in the evolution of the KRT, with the emergence of Piruru, La Galgada, Buenavista, Hualcay\u0026aacute;n and Pampa de las Llamas. La Galgada is distinguished by its multi-level temples featuring ventilated hearths and intricately carved niches, reflecting a high degree of ritual specialization. A similar, albeit less pronounced, expression is observed at Hualcay\u0026aacute;n, situated south of La Galgada. The contemporaneous occupation of Caral suggests that interactions between highland and coastal societies were limited, as each maintained distinct architectural expression. In contrast, sites such as Acshicupoto did not incorporate KRT elements despite following their established chronological trajectories. Additionally, Buenavista emerges as the southern expression of the KRT and Pampa de las Llamas emerges in the Casma valley.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eConsolidation Stage (1800\u0026thinsp;\u0026minus;\u0026thinsp;800 BCE)\u003c/h2\u003e \u003cp\u003eThis stage is represented by the consolidation of KRT structures into the coast, highlands, and Andean mountains.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003ePhase 04 (1800\u0026thinsp;\u0026minus;\u0026thinsp;1300 BCE)\u003c/h2\u003e \u003cp\u003eWhile long-standing KRT centers\u0026mdash;Huaynun\u0026aacute;, Piruru, Buenavista, Pampa de las Llamas, and Hualcay\u0026aacute;n\u0026mdash;remained active, the establishment of newly monumental nodes such as El Para\u0026iacute;so signals a fresh wave of ritual investment. The simultaneous persistence and expansion of these sites point to a moment of heightened socio-political integration in which ceremonial architecture functioned as a locus of collective identity and coordination. This integrative impulse likely emerged in response to climatic perturbations linked to ENSO variability and attendant demographic shifts, which would have intensified the demand for supra-local cooperation and shared ideological frameworks (Caramanica et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; D. Sandweiss et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; D. H. Sandweiss et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003ePhase 05 (1300\u0026thinsp;\u0026minus;\u0026thinsp;1100 BCE)\u003c/h2\u003e \u003cp\u003eDuring the late consolidation phase, only Piruru, Hualcay\u0026aacute;n, Pampa de las Llamas, El Para\u0026iacute;so, and Gramalote, continue active. Collectively, this pattern signals a pronounced regional realignment, reflecting shifting social priorities and adaptive responses to external pressures.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eDecline Stage (800\u0026thinsp;\u0026minus;\u0026thinsp;500 BCE)\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThis stage is marked by a significant decline in KRT sites across the Andes.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003ePhase 06 (800\u0026thinsp;\u0026minus;\u0026thinsp;500 BCE)\u003c/h2\u003e \u003cp\u003eIn the last phase (c. 600\u0026ndash;300 BCE) the KRT fades as a coherent tradition. Only residual temples at Chav\u0026iacute;n de Hu\u0026aacute;ntar, set apart from the main complex, keep its forms alive. This interval coincides with a severe El Ni\u0026ntilde;o and a large earthquake (~\u0026thinsp;550 BCE) in Ancash (Rick et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Isotope data from the Supe Valley reveal food stress and growing competition, eroding elite power (Pezo-Lanfranco et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Central-coast U-shaped centers were abandoned, and Chav\u0026iacute;n\u0026rsquo;s broader influence collapsed (Mesia-Montenegro, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Environmental shocks and social turmoil thus framed the final retreat of KRT ideals.\u003c/p\u003e \u003cp\u003eIn summary, the data delineates a trajectory of regional experimentation, adaptation, and eventual synthesis within the Andean cultural landscape. The robust performance of the radiocarbon model supports these chronological phases, which collectively reveal the dynamic evolution of the Kotosh Religious Tradition\u0026mdash;from its origins at Huaricanga, through regional expansion and formalization of ritual spaces, to its eventual decline and legacy in subsequent cultural expressions.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe KRT represents a pivotal phenomenon in the emergence of socio-religious complexity in the Central Andes. By integrating Bayesian chronological modeling with a geographically expansive dataset, this study challenges long-standing assumptions about the unidirectional diffusion of ritual practices and redefines the spatiotemporal dynamics of the KRT. The results reveal a near-synchronous emergence of the KRT across ecologically distinct regions (3600 Cal BCE), sustained ritual continuity through the Late Archaic and Formative periods, and multidirectional cultural exchange that reshaped regional belief systems. These findings call for a reassessment of the mechanisms behind religious innovation, the influence of environmental adaptation on cultural development, and the relationship between religion and socio-political organization in early Andean societies.\u003c/p\u003e \u003cp\u003eReassessing Cultural Diffusion and Regional Agency\u003c/p\u003e \u003cp\u003eModel A supports the simultaneous emergence of KRT-associated structures in both coastal (Creamer et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Piscitelli, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2017a\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2017b\u003c/span\u003e) and highland regions(Elizabeth Bonnier, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; R. Burger, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; R. L. Burger \u0026amp; Salazar-Burger, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e) (3600\u0026ndash;3000 Cal BCE) which in turn refutes models advocating for a unidirectional spread of religious practices. Instead, Bayesian models support multiregional syncretism, wherein shared ritual principles\u0026mdash;such as fire-centric ceremonies and ventilated hearths\u0026mdash;were adapted to local ecological and social contexts. While Model D isolates Huaricanga as the sole bearer of the KRT (peripheral to the main architectural volumes), Phase 02 of Model D reinforces a multidirectional network of KRT sites that not only expanded to Caral but also to the highlands and eastern mountains (Piruru).\u003c/p\u003e \u003cp\u003eCoastal manifestations of the KRT were characterized by the integration of ritual elements into expansive monumental complexes, designed to facilitate collective ceremonial practices and consolidate elite authority\u0026mdash;a pattern paralleled, albeit at a comparatively reduced scale, in select highland sites such as La Galgada, Acshicupoto, and Hualcay\u0026aacute;n and probably Kotosh. In contrast, other highland sites (e.g., Huaricoto, Piruru, and the northern highland site La Seductora) prioritized smaller-scale, heart-centric structures situated within communally oriented landscapes.\u003c/p\u003e \u003cp\u003eThe differences in architecture and site organization reveal that highland communities actively reshaped KRT ritual practices rather than merely copying them. Instead of being passive imitators on the margins, these communities played a significant role in reworking the tradition, tailoring its core ideas to their local environments and social needs while retaining unique ritual practices. This agency challenges older theories that view cultural practices as spreading outward from a sole source, emphasizing instead a network of interconnected regions that collectively shaped the KRT across the Andes.\u003c/p\u003e \u003cp\u003eBayesian models suggest a dynamic ideological network facilitated by cross-regional interaction, possibly through pilgrimage, resource exchange, or seasonal mobility (Mesia-Montenegro \u0026amp; Sanchez-Borjas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The presence of marine shells at highland Huaricoto, La Galgada and Huaricanga, and highland-style niches at coastal Caral (Ruth Shady, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) materializes this reciprocity, illustrating how ritual spaces functioned as nodes in a pan-Andean exchange system. Such multidirectional influence aligns with Granovetter\u0026rsquo;s theory of \u0026ldquo;weak and strong ties\u0026rdquo;, wherein intermittent interactions between distinct groups foster trust and cultural hybridization without eroding regional identities (M. S. Granovetter, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1973\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eKRT sites functioned as pivotal hubs for rituals that interconnected local communities (characterized by strong ties) and broader regional networks (defined by weak ties). These sites operated as nodes within a social and ritual network, bridging otherwise fragmented groups through shared ceremonial participation. Standardized architectural elements\u0026mdash;such as central hearths and ventilation shafts\u0026mdash;reflect a shared ritual lexicon that facilitated communication and trust among diverse populations, enabling cross-group cohesion.\u003c/p\u003e \u003cp\u003eWithin this framework, strong ties\u0026mdash;marked by close emotional bonds, frequent interaction, and mutual trust\u0026mdash;fostered solidarity within tight-knit groups. However, their dense, overlapping social circles often limited exposure to novel ideas due to redundant information flows. Conversely, weak ties (per Granovetter\u0026rsquo;s theory) provided access to non-redundant information, acting as critical bridges for innovation and intergroup exchange (M. Granovetter, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eA compelling dynamic emerges if KRT leaders strategically cultivated weak ties with peers in other communities. As brokers of social capital, leaders could selectively harness weak ties to gather external innovations or knowledge, then integrate these into their local strong-tie networks. This dual role allowed leaders to regulate information flow, modulating the openness of their communities to external influences while maintaining internal cohesion. By curating weak-tie connections, leaders balanced the introduction of new ideas with the preservation of traditional practices, thereby shaping the adaptive capacity and cultural trajectory of their groups (M. S. Granovetter, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1973\u003c/span\u003e). In this sense, Granovetter\u0026rsquo;s theory underscores that diversity in social connections\u0026mdash;not just their closeness\u0026mdash;drives innovation, opportunity, and resilience.\u003c/p\u003e \u003cp\u003eEmbedded Religiousness: Ritual as Social and Economic Infrastructure\u003c/p\u003e \u003cp\u003eThe concept of embedded religiousness is essential for understanding the lasting influence of the Kotosh Religious Tradition (KRT) in the Andean region. This framework posits that religious practices were not separate from social and economic structures but were instead deeply integrated into them. Within this system, religion functioned as a foundational mechanism for organizing authority, structuring social relationships, and directing economic activities.\u003c/p\u003e \u003cp\u003eKRT sites exemplify this integration, serving as multifunctional nodes where religious, political, and communal activities converged. Religious institutions provided a legitimizing framework for authority, embedding power within shared rituals and symbols. This, in turn, reinforced social cohesion, facilitated cooperation, and sustained hierarchical structures (Hayden, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1995\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Hayden \u0026amp; Villeneuve, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Mes\u0026iacute;a-Montenegro, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Beyond their ritual significance, these sites also played crucial economic roles, acting as hubs for resource redistribution, labor coordination, and elite legitimization. The theoretical foundation of embedded religiousness aligns, again, with Granovetter\u0026rsquo;s concept of embeddedness in economic sociology, which argues that economic transactions are governed by social norms and trust rather than purely rational self-interest. Similarly, in the Andean context, religious institutions\u0026mdash;such as those associated with the KRT\u0026mdash;functioned as authoritative centers that structured both social and economic life. By providing codified knowledge of rituals, these institutions conferred power on elites, who leveraged religious frameworks to mobilize labor and consolidate status (M. Granovetter, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1985\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eBayesian statistical models support this perspective by demonstrating the long-term continuity of ritual practices across diverse ecological zones. For example, the cyclical renovation of ceremonial hearths at Late Archaic and Formative sites from the Andean coast and highlands suggests a shared ideology of renewal that transcended environmental and temporal boundaries. These practices were operationalized through large-scale collective labor projects\u0026mdash;such as quarrying stones for platform mounds or maintaining ceremonial fires\u0026mdash;where economic activities were inseparable from religious frameworks.\u003c/p\u003e \u003cp\u003eThis interplay between religion and economy is further illuminated by Polanyi\u0026rsquo;s concept of the \u0026ldquo;embedded economy,\u0026rdquo; (Polanyi, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) which argues that economic exchange was governed by cultural norms rather than market forces. While Polanyi emphasized that economies are embedded in social relations, the concept of embedded religiousness proposes that in the Andean world, religion\u0026mdash;not the economy\u0026mdash;was the central organizing force. Religious institutions dictated key aspects of economic life, including resource allocation, labor mobilization (e.g., communal construction projects), and the formation of social hierarchies.\u003c/p\u003e \u003cp\u003eFor instance, the circulation of prestige goods at La Galgada\u0026mdash;such as spondylus ornaments\u0026mdash;was likely facilitated through religious networks, reflecting a ritualized economy where sacred practices structured exchange (Grieder, Bueno, Smith Jr, \u0026amp; Malina, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Washburn et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In this system, religious authority shaped not only symbolic meaning but also material transactions, reinforcing social differentiation through control over sacred knowledge and access to valued goods (Mesia-Montenegro \u0026amp; Sanchez-Borjas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eThe concept of embedded religiousness refines Polanyi\u0026rsquo;s critique of market fundamentalism by asserting that religion, rather than economic forces, constituted the overarching system in ancient Andean societies. Just as Polanyi cautioned against the segregation of economies from social structures, it is crucial not to treat religion as an isolated sphere. Instead, religion was the central axis around which authority and economic organization were woven into a unified cultural framework.\u003c/p\u003e \u003cp\u003eIdeology, Authority, and the Institutionalization of Religion\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe KRT\u0026rsquo;s architectural and ritual norms provided a template for institutionalizing religious authority. At coastal centers, the integration of KRT structures into monumental complexes (e.g., Caral, the Casma valley) suggests that emerging elites co-opted ritual spaces to consolidate power. The restricted access to coastal KRT altars\u0026mdash;contrasted with open plazas for communal ceremonies\u0026mdash;reflects a hierarchical ritual system where elites mediated between religious and human realms (Hayden, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1995\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2001\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Hayden \u0026amp; Villeneuve, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Conversely, highland sites like Huaricoto, La Seductora and Piruru emphasize repeated hearth renovations and communal offerings, indicating collective stewardship of ritual knowledge (Elizabeth Bonnier, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Mesia-Montenegro \u0026amp; Sanchez-Borjas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eBayesian models further illuminate how KRT practices facilitated ideological synergy during the Formative period (1800\u0026ndash;200 BCE). The late persistence of KRT elements at Chav\u0026iacute;n de Hu\u0026aacute;ntar\u0026mdash;a site renowned for its pan-regional influence\u0026mdash;demonstrates the tradition\u0026rsquo;s enduring symbolic capital. Here, the KRT structure was incorporated into a peripheral location, suggesting that earlier rituals were either supplanted or strategically retained to legitimize Chav\u0026iacute;n\u0026rsquo;s authority (D. Contreras, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Rick, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). This duality underscores the KRT\u0026rsquo;s role as both a foundational tradition and a malleable ideological tool, adaptable to shifting political landscapes.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThree questions were posed at the beginning of this paper: how can Bayesian chronological modeling in OxCal, along with rigorous chronological hygiene protocols, clarify the origins and dissemination of the Kotosh Religious Tradition (KRT). How can Bayesian chronological modeling (via OxCal), combined with stringent chronological hygiene protocols, elucidate the origins, and spread of the Kotosh Religious Tradition (KRT)? What temporal overlaps exist between early coastal KRT monumental complexes and highland ritual practices, and how do these overlaps inform patterns of cultural coexistence or ideological change? Can Bayesian analysis substantiate bidirectional cultural transmission between the coast and highlands, thereby challenging linear diffusion theories?\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003eBayesian Chronological Modeling and Chronological Hygiene Protocols\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eBayesian modeling via OxCal, combined with stringent chronological hygiene protocols, enhanced the precision of dating the Kotosh Religious Tradition (KRT) by integrating 168 radiocarbon dates from sixteen sites. Chronological hygiene excludes low-reliability dates (e.g., large σ or unclear contexts), focusing on high-quality data (e.g., clear, and traceable contexts). This approach reduced uncertainty, enabling robust phased models that revealed the KRT emerged simultaneously on the central coast and highlands by 3500 Cal BCE. The analysis demonstrated rapid coastal innovation (e.g., monumental complexes) and concurrent highland adoption with localized adaptations (e.g., smaller heart-centered structures). By resolving ambiguities in temporal sequencing, Bayesian methods provided a unified chronology, challenging assumptions of unidirectional diffusion and highlighting regional synchronicity in KRT origins. This Bayesian hygiene workflow can be adapted to other under-dated contexts to assess whether similar synchronicity patterns occurred elsewhere.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eTemporal Overlaps and Cultural Coexistence:\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe Bayesian models identified significant temporal overlaps between coastal and highland KRT sites. Coastal monumental complexes (e.g., Huaricanga) and highland ritual practices (e.g., Huaricoto) emerged contemporaneously (3600\u0026ndash;3000 cal BCE). Coastal sites prioritized large-scale ceremonial architecture (e.g., sunken plazas), while highland sites emphasized intimate fire ritual spaces. These overlaps indicate cultural coexistence rather than displacement, with regions adapting KRT to ecological and sociopolitical contexts. The sustained overlap, even well into the fifth phase, reflects ideological synergy, where shared ritual elements persisted alongside regional divergences.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eBidirectional Cultural Transmission:\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eBayesian chronological modeling challenges unilinear diffusion paradigms, demonstrating cultural transmission between coastal and highland KRT sites. The analysis reveals that highland communities innovatively adapted KRT ritual principles\u0026mdash;such as specialized ventilation systems\u0026mdash;into multifunctional administrative and ceremonial spaces, which were later reincorporated into coastal architectural repertoires.\u003c/p\u003e\u003cp\u003eThis reciprocity materialized in shared features (e.g., ritual hearths, wall niches) and overlapping site chronologies, reflecting sustained interaction rather than unidirectional influence. Persistent weak-tie networks (sensu Granovetter) between regions facilitated the integration of localized \u0026ldquo;strong-tie\u0026rdquo; practices into a broader ideological framework. By situating highland regions as dynamic co-responsible of KRT development, the study underscores environmental diversity and cross-regional mediation as catalysts for ritual and organizational complexity in the pre-Hispanic Andes.\u003c/p\u003e\u003cp\u003eFinally, the KRT emerged as a pan-Andean ritual and architectural phenomenon, characterized by ceremonial structures with central hearths, ventilated chambers, split-level floors, and plastered walls. Its evolution reflects adaptive syncretism between highland religious practices and coastal monumentality, shaped by environmental, social, and ideological dynamics.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eChristian Mes\u0026iacute;a-Montenegro: Writing \u0026ndash; review \u0026amp; editing. Visualization, Validation, Supervision, Software, Resources, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eTo all researchers who openly share their data, advocate open science, and open data practices, and to the reviewers whose feedback has enhanced the quality of this paper. To the Universidad Privada del Norte which provided time and resources for undertaking this research. Any mistakes are entirely my own.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data, OxCal and R codes are provided as supplementary information.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBayliss A, Ramsey CB, Van der Plicht J, Whittle A (2007) Bradshaw and Bayes: towards a timetable for the Neolithic. 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University of Chicago Press, Chicago\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"archaeological-and-anthropological-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aasc","sideBox":"Learn more about [Archaeological and Anthropological Sciences](http://link.springer.com/journal/12517)","snPcode":"12520","submissionUrl":"https://submission.nature.com/new-submission/12520/3","title":"Archaeological and Anthropological Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6896121/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6896121/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBayesian chronological modelling offers new leverage for reassessing the tempo and trajectory of early Andean ritual systems. Here I re-evaluate 168 radiocarbon determinations from 16 Late Archaic and Formative sites associated with the Kotosh Religious Tradition (KRT) using an OxCal workflow that combines rigorous sample vetting, outlier modelling, and Monte Carlo\u0026ndash;derived Kernel Density Estimation. The resulting high-precision sequences reveal that KRT ceremonial architecture arose virtually simultaneously on Peru\u0026rsquo;s central coast and in the adjacent highlands by ~\u0026thinsp;3600 cal BCE, refuting long-standing diffusionist scenarios that posit a unidirectional spread from one heartland to another. Six statistically robust ritual phases are defined, each bracketed by \u0026ge;\u0026thinsp;95% highest-posterior-density intervals. Probability distributions for phase boundaries and inter-regional offsets indicate recurrent, multidirectional exchange rather than linear succession. This pattern implies a distributed network of communities negotiating a shared but diversely expressed ritual repertoire, rather than a single center exporting an ideological package. Beyond clarifying KRT chronology, the study demonstrates how transparent \u0026ldquo;chronological hygiene\u0026rdquo; protocols paired with Bayesian phase-break analysis can resolve fine-grained cultural dynamics in other early complex societies.\u003c/p\u003e","manuscriptTitle":"Time, Ritual, and Bayesian Reasoning: Charting the Andean Kotosh Religious Tradition","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-18 14:37:53","doi":"10.21203/rs.3.rs-6896121/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-07-28T06:45:57+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-23T20:19:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"209703107665819334632711173627174946552","date":"2025-07-18T13:01:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-13T07:00:48+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-16T13:38:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-16T07:12:47+00:00","index":"","fulltext":""},{"type":"submitted","content":"Archaeological and Anthropological Sciences","date":"2025-06-15T02:36:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"archaeological-and-anthropological-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aasc","sideBox":"Learn more about [Archaeological and Anthropological Sciences](http://link.springer.com/journal/12517)","snPcode":"12520","submissionUrl":"https://submission.nature.com/new-submission/12520/3","title":"Archaeological and Anthropological Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"611fbd35-4251-4e26-8e8e-7566384474d3","owner":[],"postedDate":"July 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-08T16:01:11+00:00","versionOfRecord":{"articleIdentity":"rs-6896121","link":"https://doi.org/10.1007/s12520-025-02370-9","journal":{"identity":"archaeological-and-anthropological-sciences","isVorOnly":false,"title":"Archaeological and Anthropological Sciences"},"publishedOn":"2025-12-02 15:57:39","publishedOnDateReadable":"December 2nd, 2025"},"versionCreatedAt":"2025-07-18 14:37:53","video":"","vorDoi":"10.1007/s12520-025-02370-9","vorDoiUrl":"https://doi.org/10.1007/s12520-025-02370-9","workflowStages":[]},"version":"v1","identity":"rs-6896121","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6896121","identity":"rs-6896121","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}