Athabascan language group people of United States southwest. Their intrusion from Northwestern subarctic areas of Canada, c 900-1200 AD, helped bring about the abandonment of Pueblos in Anasazi subarea. They were probably aided by groups of Apache Indians, also Athabascans, moving into southwest at that time. The Navajo speak an Apachean language, which, like the language of their Apache cousins, is classified in the Athabascan family.