Proto-Dené–Caucasian is the reconstructed hypothetical common ancestor of the Dené–Caucasian languages, a proposed language superfamily to which Basque, North Caucasian, Burushaski, Sino-Tibetan, Yeniseian, Na-Dené and possibly also other language families may belong. Dene-Caucasian is not supported by most historical linguists and is generally regarded as a fringe theory.