We report 21 genomes (1240k SNPs) from 21 individuals that lived and were buried in the Chincha Valley, Peru, dating between the 13th and 15th century CE. .
This paper tracks long-distance migration on the Pacific coast that began no later than the thirteenth century CE. Genome-wide data for all 21 sampled individuals from the Chincha Valley of southern Peru show shared ancestry with groups ~700 km to the north. The earliest migrants have unadmixed ancestry, whereas in subsequent generations, intermarriage produced admixtures from neighboring coastal areas. Relatives buried together in a family ossuary practiced consanguineous endogamy. We built a generation-scale Bayesian model informed by an aDNA-based family tree and individual calibration curves for estimated proportions of marine diet, overcoming long-standing difficulties with temporal precision on the Pacific coast. These data demonstrate population continuity from the thirteenth to fifteenth centuries, coinciding with persistent traditions of cranial modification and postmortem red pigment application. We reveal close-knit and far-reaching coastal interaction networks that shaped the sociopolitical landscape encountered by Inca emissaries before they integrated these communities into their empire.