Fig. 5. Genetic links between Tibeto-Burman speakers.

Tibetan groups from the Plateau and the Himalayas form a genetic cline, with the two poles represented by present-day Nepalese Tibetans (as well as aMMD) and Upper_YR_LN (“the Tibetan cline”). The non-Tibetan Tibeto-Burman cline reflects admixture along the circum-Plateau route and includes mid-altitude populations such as Naxi, Yi, Naga, Tamang and Gurung. Naxi and Yi cannot be modeled as a part of the Tibetan cline, i.e., Tsum+Upper_YR_LN; instead, YR_MN alone adequately models them. Non-Tibetan Tibeto-Burman speakers have higher contribution from the Tibetan lineage (represented by Nepalese Tibetan Tsum), and far-western mid-altitude populations Tamang and Gurung further have South Asian influx. Squares indicate the source populations used in ancestry models (circles).