Crossing Borders: Selected Papers from the 13th International Conference of the European Association of Southeast Asian Archaeologists

Chapter 13: A New Chronological Framework for Ban Chiang, Northeast Thailand

164 Charles F.W. Higham and Thomas F.G. Higham Chapter 13 A New Chronological Framework for Ban Chiang, Northeast Thailand Charles F.W. Higham and Thomas F.G. Higham Abstract With each new generation of developments in radiocarbon dating, old interpretations must be reevaluated . Major advances have included AMS (Accelerator Mass Spectrometry) dating, the application of Bayesian statistics and the pre-treatment of bone through ultrafiltration. Currently in Southeast Asia, we have entered a new and dynamic period of enquiry made possible through these seminal changes, nowhere better illustrated, than by comparing the results of successive dating programs at the site of Ban Chiang, and their cultural implications. Introduction There have been three attempts to secure a proper chronological framework for this site. Located in Northeast Thailand, it assumed world prominence when, following excavations in 1974–5, Chester Gorman and Pisit Charoenwongsa (1976) claimed that the Bronze Age began at this site in about 3600 BC, and the Iron Age in the middle of the second millennium BC. As a member of the excavation team, I (CH) was witness to the collection of fragments of charcoal from grave fill in order to assemble a large enough quantity for conventional radiocarbon dating. The results were internally contradictory and defy rational interpretation [Fig. 13.1]. With the benefit of hindsight, this should not surprise: the charcoal in question came from manifestly disturbed contexts and had an unknown degree of inbuilt age. Following the death of Gorman in 1981, the University Museum of Pennsylvania appointed Joyce White to take responsibility for the analysis and publication of our excavations. Over the last 30 years, she has engaged in a new AMS dating initiative, this time involving the organic fraction of ceramic vessels from human burials, while one determination comes from rice phytolith residue (Glusker & White 1997). The former technique was seen as a major breakthrough at that time, since the pots come from an assured context and the rice chaff temper is unlikely to have an inbuilt age. Ban Chiang has a highly opaque stratigraphic sequence due to bioturbation and human disturbance in antiquity, but the superposition of graves allowed White to propose three periods of occupation subdivided into a series of phases that encompass the Neolithic, Bronze and Iron Ages [Table 13.1]. Attempts to compare phytolith radiocarbon ages with independent chronologies have revealed significant problems thought to be related to the methods used in the phytolith extraction process. Clearly, this material is not, at present, a reliable one for independent age determination and much further work is required to demonstrate this (Santos et al. 2009). Dan Glusker and Joyce White (1997) also experimented with two principal methods of pretreating the organic fraction of potsherds. The first involved teasing fragments of rice chaff out of the pottery matrix and then treating the sample with acetone, 0.2 N HCl and 0.5 N NaOH successively to extract lipids, carbonates and humic acids. In the second pretreatment (treatment B) the above procedure was applied to crushed potsherds, and followed by either a mixture of 4 M HF in 6 M HCl or concentrated hydrofluoric acid followed by multiple washings. This procedure “aims to concentrate the carbon content of the residue and also makes soluble a considerable quantity of clay-bound humic material” (see comments by Glusker and White in Hedges et al. 1997). 164 Crossing Borders hi res combined164 164 8/23/2012 7:45:59 PM 165 A New Chronological Framework for Ban Chiang Fig. 13.1: The charcoal radiocarbon dates derived from Ban Chiang burials. EPII EPIIIIV EPIV EPV MPVI MPVII LPIX OxCal v4.1.6. Bronk Ramsey (2009); r:5 Atmospheric data from Reimer et al. (2009) Calibrated data (cal BC / cal AD) Table 13.1: The cultural sequence of Ban Chiang (after Pietrusewsky and Douglas 2002: 5) Burial phase Date according to White (1997, 2008) Major period* Late Period X 300 BC–200 AD Late Period IX Iron Age Middle Period VIII 900 BC–300 BC Middle Period VII Middle Period VI Early Period V 2100 BC–900 BC Bronze Age Early Period IV Early Period III Early Period II Neolithic Early Period I Note: *As far as can be ascertained by CH. Crossing Borders hi res combined165 165 8/23/2012 7:45:59 PM 166 Charles F.W. Higham and Thomas F.G. Higham The resulting determinations, distinguished by the pretreatment method, are set out in...