In this paper, we present a paleodemographic interpretation of a complete mortuary population from the site of Rio Muerto (southern Peru) affiliated with the early Andean Tiwanaku state (A.D.500–1000). Although advances in biogeochemical paleomobility studies have revolutionized bioarchaeological approaches to certain aspects of migration, paleodemography continues to offer a valuable complementary perspective on migration and population dynamics. Notably, paleodemography, through reference to Uniformitarian age‐at‐death profiles, is uniquely equipped to identify age‐specific subgroups that are missing from the mortuary population. We argue that the marked absence of adult individuals in the M70B cemetery population is the result of the socially regulated movement of older adults or their remains from the state provinces back to the homeland. We suggest that the particular demographic composition of the Rio Muerto M70 cemetery population, when considered within its cultural context and compared to other available paleodemographic data, reveals potential patterns of adult return migration, and carries important implications for the political and social dynamics of early Andean state society. Copyright © 2015 John Wiley & Sons, Ltd.