The Ancient Beringian lineage is extinct, and is not found as a contribution to modern indigenous lineages in Alaska. The 2018 study suggests that the AB lineage was replaced by or absorbed in a back-migration of NNA (see below) to Alaska. The modern Athabaskan populations are derived from an admixture of this NNA back-migration and a Paleo-Siberian (Early Paleo-Eskimo) lineage before about 2,500 years ago.[3]