AMS Radiocarbon Dates and Bayesian Modelling From Pachkhed: Refining Early Iron Age Chronology in Vidarbha, Maharashtra, India

Abstract

ABSTRACT Reliable absolute chronologies for the Early Iron Age in Vidarbha, eastern Maharashtra, have long remained constrained by dependence on ceramic typology, relative stratigraphy and unmodelled radiocarbon determinations derived from bulk charcoal. This study presents eight new AMS radiocarbon determinations from Pachkhed, a stratified multi‐period habitation site in Yavatmal District, obtained from stratigraphically secure Early Iron Age (Period IA) contexts, including a charred rice grain recovered in situ from a compact lime floor. All eight determinations were calibrated using the IntCal20 Northern Hemisphere calibration curve and analysed within a formal Bayesian phase model implemented in OxCal v4.4.4. The model employs a general outlier model specification with a Student's t ‐distribution, uniform scale prior and material‐type‐differentiated individual outlier priors to formally incorporate prior knowledge about inbuilt age susceptibility. The primary model constrains the onset of Early Iron Age occupation to 825–775 cal bce and its termination to 794–745 cal bce (95.4% probability), with overall model agreement indices of A model = 170.2 and A overall = 176.9. The formal duration of the phase, calculated using the OxCal Span command, is estimated at 0–51 years (95.4% probability). A sensitivity model excluding a probable outlier determination produces virtually identical boundary estimates (811–772 cal bce start; 791–746 cal bce end), confirming the robustness of these results. The Pachkhed sequence provides the first formally modelled, short‐lived‐material‐based AMS chronology for an Early Iron Age habitation site in Vidarbha and serves as a methodological and empirical reference for radiocarbon‐based chronology building in the region.