Tibetic languages
Tournadre (2014) classifies Basum (Bake) as an unclassified Bodish language that does not belong to the Tibetic branch. Tournadre (2014: 112) notes that Basum has the negator "a"-, as opposed to the negator "ma"- or "myi"- in Tibetic languages. Also, unlike Tibetic languages, Basum does not palatalize Proto-Bodish *ti- and *si-.