Abstract
The Upper Mun River Valley (UMRV), located in Northeast (NE) Thailand, underwent a transition from hunter-gatherer occupation to the formation of early settlements during the Neolithic. Social development continued through the Bronze Age (BA) and into Iron Age (IA), culminating in state formation and the Angkorian Kingdom. With social transitions and technological change came biosocial adaptation, such as improving agricultural techniques, land modification in the form of moating for irrigation, concepts of land ownership, and potentially increased social inequality.
This thesis focuses on the UMRV moated site, Non Ban Jak (NBJ), a site primarily occupation during the late IA. NBJ is one of the largest and best-preserved, skeletal assemblages from the IA period in the region. By using isotopic analysis of human and faunal dental enamel, this thesis aims to better understand the relationship between human socio-economic, agricultural, and environmental change during the IA. This investigation is categorised into three main themes: subsistence, population interaction, and environmental change.
Theme one, Subsistence, has been explored using carbon and oxygen isotope analysis to identify dietary trends of the human population in addition to a subsample of animal species . Carbon (𝛿13C) isotope results indicate that the population was mostly subsisting on C3 crops, likely rice, with moderate inclusion of C4 resources. The C4 contribution could be from consumed animal protein, as many fauna were subsisting on predominately C4 plants. Oxygen (𝛿18O) isotope results from NBJ, compared with the BA occupation at Ban Non Wat (BNW), highlight a greater amount of isotopic variability at NBJ, which could be explained by increased variability in monsoon intensity or the introduction of standing water sources.
Theme two, Population Interaction, was tested using the isotopic system strontium (87Sr/86Sr). A new strontium isotope baseline, commonly referred to as an isoscape, was developed using plant, soil, and geological samples to establish a series of ‘local’ isotopic ranges for the UMRV and for six nearby archaeological sites sampled in the UMRV. All humans from NBJ were found to be from the UMRV. However, many had 87Sr/86Sr signatures which did not fall into the local NBJ range. When previously published nearby sites (BNW and NUL) were re-examined against these new baseline data, similar patterns of individuals falling outside their burial site’s baseline were identified. This suggests that there may have existed some form of intraregional subsistence or mobility. Faunal strontium isotope analysis identified three clear outliers, two bovids and one Sus scrofa. These faunal outliers, suggests that long-distance trade of food resources may have been occurring during the IA.
Examination of theme three, Environmental Change, involved the use of incremental 𝛿13C and 𝛿18O isotope analysis. Incremental sampling of animal and human dental enamel allowed the identification of possible changes in water availability through an individual’s period of tooth formation. Capturing the full modern monsoon oxygen shift, and bovid intratooth oxygen variation, suggest there was less precipitation change between wet and dry seasons during the early and late IA. The early occupation period of NBJ corresponds with a time of moat-building and therefore this isotopic evidence supports the idea that moating was a social response for the continuation of rice agriculture during times of low rainfall. Incremental isotopic analysis also contributed to understanding of birth seasonality and management of herds as well as faunal mobility during the IA.
Overall, this thesis contributes to and expands on the models of social change previously developed in the UMRV, which posit that shifting economic strategies may have been linked to environmental change during the IA.