Two great taxonomic problems must be considered in connection with Sino-Tibetan, viz. the nature of the affiliations of the three primary groups, and the classification of the multitudinous divisions within Tibeto-Burman itself. The former of these problems has been resolved in the following manner. Tibeto-Burman and Karen are regarded as constituting a superfamily (Tibeto-Karen) standing in opposition to Chinese. The relationship between Tibeto-Karen and Chinese is a distant one, comparable with that between Semitic and Hamitic, or between Altaic and Uralic. Karen, on the other hand, stands in relation to Tibeto-Burman much as Hittite stands in relation to Indo-European, i.e. Tibeto-Karen is on the same taxonomic level as Indo-Hittite. On the negative side, Sino-Tibetan must be kept distinct from all other linguistic stocks.

The writer has recently attempted to show that Thai is related to Indonesian rather than to Chinese, and that the traditional view of a Chinese-Thai relationship must be abandoned. A number of students, including Ramstedt, Donner, Lewy, Bouda, and Findeisen, have sought to connect Yenisei-Ostyak (Ket) with Sino-Tibetan, and this view has gained some favor (Schmidt, Trombetti), yet a critical examination of the evidence strongly indicates that the two stocks have nothing in common. Sporadic attempts to connect Sino-Tibetan with Caucasic (Hodgson, Bouda), Mon-Khmer (Conrady), or other linguistic families have been equally unsuccessful.