Investigating mobility and pastoralism in Kerma-period communities upstream of the fourth cataract, Sudan

Objectives: The Kingdom of Kush in today's northern Sudan and southern Egypt (ancient Nubia) is often depicted as a secondary state relative to ancient Egypt. More recent investigations have set aside Egyptocentric and western, colonialist perspectives of state development focused on control of land and agricultural surplus, examining Kushites through the lens of African-based models of mobile pastoralism in which power and authority were achieved through control of herds and alliance-building. Here, analyses of radiogenic strontium isotopes in human dental enamel are used to investigate diachronic shifts in mobility patterns linked to pastoralism and state development during the Kerma period (ca. 2500-1100 BCE). Materials and Methods: From five cemetery sites around al Qinifab, Sudan, upstream of the capital at Kerma, we analyzed the strontium isotope ratios of 50 teeth from 27 individuals dating from the Early through Late Kerma phases. Results: Individuals from the Early and Middle Kerma phases demonstrated considerable Sr-87/Sr-86 ratio variability (mean = 0.70835 +/- 0.00109), with 50% falling outside the locally bioavailable strontium range. Conversely, most Classic (0.70756 +/- 0.00043) and Late Kerma (0.70755 +/- 0.00036) individuals exhibited ratios consistent with the local region. Discussion: These changes indicate a potential transformation in subsistence strategies and social organization as early communities engaged in a more mobile lifestyle than later groups, suggesting a greater degree of pastoralism followed by declining mobility with Kushite state coalescence and a shift to agropastoralism. Because Sr-87/Sr-86 ratios from enamel reflect childhood geographic residence, these findings indicate that mobility likely involved extended family groups, and not just transhumant adults.