Lepcha

Lepcha has a very distinct Western Sino-Tibetan superstratum and Northern Austroasiatic substratum. The Western Sino-Tibetan branch forming the superstratum of Lepcha is likely an early split, as Lepcha cannot be definitively grouped with any neighboring Sino-Tibetan branches. The Austroasiatic substratum in Lepcha has been analyzed in detail by Roger Blench, who considers it to have originated from a "missing" Austroasiatic branch that he refers to as "Rongic."

Sources

Blench, Roger. 2013. Rongic: a vanished branch of Austroasiatic. Manuscript.