According to L. Bat-Ochir Bold (Academy of Science of Mongolia), there are approximately 500 Tsaatan people living in Mongolia. They do not introduce themselves as Tsaatan, especially not to Darkhad and Uriankhai, who, almost as a rule, consider [them] a very strange and uncultured people.... The Tsaatan are somewhat familiar with the Mongolian language, but they have managed to preserve their unique 'Tsaatan' language among themselves. According to Bold, the Tsaatan language shares strong linguistic ties with the ancient 'Uigur' language.The worldwide charity and ecotourism industrial complex seems to have the Tsaatan firmly in its sights, but their linguistic affiliation remains obscure. Ethnologue does not list Tsaatan even as an alternate name of any of the languages in Mongolia. Among the languages in Hövsgöl Aimag, north Mongolia, it lists Darkhat, an eastern Mongolian language with about 4,500 speakers (1956 census); Uriankhai, an alternate name for Tuvin (Tuvan), a northern Turkic language with about 27,000 speakers (1993 source); and Uyghur, an eastern Turkic language with only 1,000 speakers (1982 est.) in Mongolia, but more than 7,200,000 in China (1990 census).
Color me cynical, but I wonder if the "Tsaatan language" isn't being deliberately exoticized, along with everything else about the Tsaatan people and their unique lifestyle.