Tibeto-Burman languages
Proto-Tibeto-Burman (commonly abbreviated PTB) is the reconstructed ancestor of the Tibeto-Burman languages, that is, the Sino-Tibetan languages except for Chinese. An initial reconstruction was produced by Paul K. Benedict and since refined by James Matisoff. Several other researchers argue that the Tibeto-Burman languages "sans" Chinese do not constitute a monophyletic group within Sino-Tibetan, and therefore that Proto-Tibeto-Burman was the same language as Proto-Sino-Tibetan.