Reconstruction of the EIA Toutswe environment through stable isotopes

East central Botswana is well known for some of the earliest and most prosperous Early Iron Age settlements in southern Africa. The Toutswe communities flourished between AD700 and 1000. Archaeological evidence shows that these communities thrived through control of trade between the Indian Ocean and the interior as well as rearing livestock. Herd populations proliferated under good climatic and environmental conditions. It was initially thought that the subsequent collapsed of the Toutswe polity was caused by change in climate and environment. In this study, stable isotope analyses of archaeological and modern domestic herbivores were conducted to reconstruct the climate and environment of the Toutswe area from its inception to subsequent collapse. Mean δ15N values of about 7‰ suggest annual rainfall of about 500mm throughout the Toutswe period. Carbon δ13C values of cattle from all periods average -6‰ and thereby indicating that these animals were raised on pure C4 photosynthetic grasses. Both nitrogen and carbon isotope result reflect good climatic conditions associated with good pastures throughout. Therefore, the collapse of the Toutswe polity was most probably due to change in trade networks, internal conflicts and other factors.