An examination of the aboriginal core culture of the Athapaskans of the Yukon Plateau—the Koyukon, Kolchan, Tanana, and Ingalik. It is proposed that the matrilineal basis of the social organization is ancient and a part of the aboriginal culture of Alaskan Athapaskans, if not all Dene-speakers, and that it is functionally related to the mobile hunting patterns of the Dene. It is further suggested that where other forms of social structure replace the matrilineal emphasis, this is related to a shift toward a less mobile seasonal round with an accompanying change in subsistence patterns.