The genetic landscape of northeastern Iberian communities from the early to late Iron Age.

During the Iron Age (800-100 BCE), northeastern Iberia was shaped by interactions among local communities and Mediterranean societies. Iberian cultural traditions developed along the coast from the sixth century BCE and persisted through major social transformations leading into the Roman period. We analyzed ancient genomic data from 54 newborn burials recovered beneath domestic structures at three sites spanning the early Iron Age to the early Roman period (775 BCE-50 CE). Genome-wide data were obtained for 22 individuals, with additional mitochondrial haplogroups for nine more. The results indicate genetic continuity from Bronze Age-derived local populations through the Iron Age, accompanied by increasing Mediterranean-related ancestry. This population structure remained largely stable until Roman expansion, after which additional genetic inputs contributed to a more heterogeneous population. These findings link long-term cultural continuity with gradual genetic change and illuminate population dynamics during a key period of social and political transition in northeastern Iberia.