Isotopic Evidence for Socio-economic Dynamics Within the Capital of the Kingdom of Alwa, Sudan

Between the sixth and fifteenth c. CE, a vast expanse of central and southern Sudan belonged to the kingdom of Alwa, ruled from the urban metropolis of Soba. Renewed investigation of the city unearthed a small cemetery in the northern part of the site. The heterogeneity of burial practices raised some questions as to the cultural and religious affinities of the deceased and suggested potential multiculturalism of the local urban population. We applied isotopic analyses to investigate the origins of the people buried at Cemetery OS and their concomitant ways of life. Non-concordance of ⁸⁷Sr/⁸⁶Sr and δ¹⁸O values with local hydro-geological background speaks to the mixing of water sources as a result of residential mobility. The concordance of human and faunal strontium and oxygen results, combined with elevated δ¹³C values corresponding to almost exclusive reliance on C₄ produce, points to the possibility of seasonal movement of people with their herds between the Nile valley and the adjacent grasslands. Despite the turn of the medieval Nubian economy towards settled agriculture, by revealing the granular specificities of human adaptation in challenging ecosystems, our results produce the first insight into the enduring diversification of economic production, even in urbanized settings, and persisting participation of local peoples in agro-pastoral symbiosis.