 The Arctic Small Tool tradition source may have been the Syalakh-Bel’kachi-Ymyakhtakh culture sequence of East Siberia, dated to 6,500 – 2,800 calBP.The interior route is consistent with the spread of the Na-Dene language group< and subhaplogroup X2a into the Americas after the earliest paleoamerican migration.Nevertheless, some scholars suggest that the ancestors of western North Americans speaking Na-Dene languages made a coastal migration by boat.