We present the results of strontium isotope analysis conducted on human individuals recovered at the Huaca 20 sector of the Maranga Complex; a Late Lima settlement of the Lower Rimac Valley that flourished during the Middle Horizon Epoch 1 (600–800 CE). Our aim is to evaluate the diversity of the Huaca 20 population through an integrated approach that combines contextual analysis of burials’ associations, the bioarchaeological characterization of the buried individuals and the acquisition of 87Sr/86Sr compositions of individuals’ tooth enamel to explore early-life values and probable geographic origins. Our results reveal a scenario of a mainly local population with a minority of foreign individuals that suggest mobility consistent with post marital residential patterns. The lack of correlation between individual’s origins and a diversity of burial practices and associations (as for example, foreign umber ware ceramics) suggests that mobility might have occurred as a continuous phenomenon, which resulted in a cosmopolitan population, generated under regional interactions that occurred beyond elite control.