Oscillating diachronic mobility patterns in prehistoric Eastern Sudan revealed by 87Sr/86Sr isotope analysis

During the Holocene, Eastern Sudan functioned as a cultural and ecological crossroads throughout northeastern Africa. However, despite its significance, the region has remained largely unexplored in terms of human mobility studies through isotope analyses. This research addresses this gap by analysing ⁸⁷Sr/⁸⁶Sr ratios in human and faunal remains from three key archaeological sites – Upper Atbara 50 (UA50), Upper Atbara 53 (UA53), and Mahal Teglinos (K1). Spanning five cultural phases and over four millennia – UA50, Malawiya Group (second half of the 5th millennium BCE); UA53, Butana Group (late 4th millennium BCE); K1, Gash Group (early 3rd –early 2nd millennium BCE); Jebel Mokram Group (early 2nd millennium BCE–early 1st millennium CE); and Hagiz Group (first half of the 1st millennium CE) – these data offer novel insights into the diachronic patterns of mobility and interaction that shaped the Eastern Sudanese lowlands during the Mesolithic and the Neolithic. Results reveal a complex diachronic pattern of human mobility. High levels of individual mobility during the late Mesolithic likely reflect a nomadic lifestyle, which progressively shifted towards greater sedentism in the Neolithic, associated with the adoption of agriculture and animal husbandry, as well as the establishment of larger sites. In the 3rd and 2nd millennia BCE, the site K1 likely functioned as a key regional hub, facilitating interactions between different communities, as evidenced by the adoption of diverse funerary practices and the wide range of ⁸⁷Sr/⁸⁶Sr isotope signatures among individuals identified as mobile. From the 2nd millennium BCE, harsher environmental conditions and shifts in socio-economic dynamics in northeastern Africa prompted a return to more nomadic pastoral lifeways. In Eastern Sudan, proximity to the Ethio-Eritrean highlands may have mitigated the effects of aridification, making this region a potential shelter region that attracted groups from the Eastern Desert, where environmental stress was likely more severe or occurred earlier. This study establishes a preliminary isotopic baseline for Eastern Sudan and provides new insights into long-term patterns of mobility and interaction. It complements existing archaeological data and offers a robust framework for future multidisciplinary investigations into exchange networks and cultural resilience in this pivotal region of northeastern Africa.