Strontium isotope (87Sr/86Sr) variability in the Nile Valley: identifying residential mobility during ancient Egyptian and Nubian sociopolitical changes in the New Kingdom and Napatan periods.

As a successful technique for identifying residential mobility in other areas, this study investigates the feasibility of using 87Sr/86Sr analysis to track the movements of the ancient peoples of Egypt and Nubia in the Nile Valley, who interacted via trade, warfare, and political occupations over millennia. Dental enamel from faunal remains is used to examine variability in strontium sources in seven regional sites; human enamel samples are analyzed from eight Nile Valley sites in order to trace human movements. The faunal samples show a wide range of 87Sr/86Sr values demonstrating that some animals were raised in a variety of locales. The results of the human samples reveal overlap in 87Sr/86Sr values between Egyptian and Nubian sites; however, Egyptian 87Sr/86Sr values (mean/median [0.70777], sd [0.00027]) are statistically higher than the Nubian 87Sr/86Sr values (mean [0.70762], median [0.70757], sd [0.00036], suggesting that it is possible to identify if immigrant Egyptians were present at Nubian sites. Samples examined from the site of Tombos provide important information regarding the sociopolitical activities during the New Kingdom and Napatan periods. Based on a newly established local 87Sr/86Sr range, human values, and bioarchaeological evidence, this study confirms the preliminary idea that immigrants, likely from Egypt, were present during the Egyptian New Kingdom occupation of Nubia. In the subsequent Napatan period when Nubia ruled Egypt as the 25th Dynasty, 87Sr/86Sr values are statistically different from the New Kingdom component and indicate that only locals were present at Tombos during this developmental time.