Form-plus-fabric : northeast Thailand ceramic technology from the Bronze to Iron Ages

Accompanying material available with hardcopy.This study traced changes in the form and fabric of ceramics vessels from the Bronze to Iron Age at Ban Non Wat, Khorat Plateau, Northeast Thailand. A complementary ethnoarchaeological component assessed modern ceramic fabrics and manufacturing techniques from the nearby potting village, Ban Thakok, in order to infer behaviours of prehistoric potters. Mortuary ceramics were sampled from the cultural phases, Bronze Age 1 to 4 and Iron Age 1 to 2, for form-plus-fabric analysis. 'Form-plus-fabric' brings together stylistic studies (form) and scientific research strategies (fabric or paste). The aim was to characterise vessel form and fabric changes through time. The notable difference between Bronze and Iron Age pot forms was the foundation for an investigation of whether there was a sudden or gradual change in ceramic technology as these forms modified. Both cultural (form) and technological (fabric) attribute analyses were required to place ceramic traditions within the changing socio-political environment into the Iron Age. Ceramic vessels were stylistically analysed by recording form, size and surface treatment in the field and from photographs. Eighteen vessel form groups were identified. Ceramic fabric analysis utilised the electron microprobe Energy Dispersive Spectrometer and microscopic imaging to identify temper choices, natural non-plastic inclusions of the potting clay and the clay matrix composition, followed by a Principal Component Analysis. Untempered and quartz sand, rice husk, grog and shell tempered wares made from chemically similar local clays were identified. The local clays were subdivided into ten groups. Analysis of upper and lower portions of the same vessel revealed that some composite pots comprised multiple fabrics, inclusive of different tempering methods. This discovery justifies the collection and recording of multiple diagnostic sherds from a single vessel. Local raw clay sources were sampled and comparisons between clay matrix compositions within prehistoric ceramics and clay sources revealed they were chemically similar. Observations at Ban Thakok revealed that rice chaff tempers and local clays were applied in both prehistoric and modern potting fabrics. Greater processing of the temper was evident in modern ceramic manufacture. These similar practices for clay and temper selection suggest continuity in ceramic technology from the past to the present. A ceramic technology sequence based on form and fabric findings was established for the Bronze and Iron ages at Ban Non Wat. Rice temper introductions mark the earliest change in ceramic technology at the advent of Bronze Age 3, around 790 BC. This is the earliest postulated date for rice tempering on the Khorat Plateau and was simultaneous with fewer exotic goods and a shift in mortuary treatments. Vessel forms associated with the Iron Age were present from Bronze Age 4. Clay selection was local throughout the sequence, however some diversification in sourcing from Iron Age 1 suggests there was a greater demand for clay in craft industries from this time. Mortuary practices continued to change from Bronze Age 4. The results demonstrated that there was a gradual transition from Bronze to Iron Age ceramic traditions, and certain prehistoric traditions persist to the present in Northeast Thailand