Ancient genomes reveal an extensive kinship network and endogamy in a Three-Kingdoms period society in Korea

The burial complex of the Imdang-Joyeong site at Gyeongsan in southeastern Korea is notable for the large number of tombs constructed within ~100 years (4th-6th centuries CE) as well as widespread practice of human sacrifice. Analyzing genome-wide data from 78 individuals, we detected 11, 23, 20 pairs of the first, second, and three-or-more-distant degree relatives, respectively, revealing a dense network of kinship in the Imdang-Joyeong society. We found 5 individuals from closely related parents, suggesting the practice of consanguineous marriage in both grave owners and the sacrificed. We also observed adult female descendants buried together with their kin, unlike several recent archaeogenetic studies in Europe reporting a strict pattern of female exogamy. We detected no discernible genetic difference between grave owners and the sacrificed. Our analysis provides novel bioarchaeological information on the burial customs and social structure of the Three-Kingdoms period society in Korea.