Dené–Caucasian is a proposed broad language family that includes the Sino-Tibetan, North Caucasian, Na-Dené, Yeniseian, Vasconic (including Basque), and Burushaski language families. A connection specifically between Na-Dené and Yeniseian (Dené–Yeniseian languages hypothesis) was proposed by Edward Vajda in 2008, and has met with some acceptance. The validity of the rest of the family, however, is rejected or viewed as doubtful by most historical linguists.