Wikipedia
Gyami
The Gyami snw: ग्यामी (Gyámi, Tibetan for "Chinese") were a Han Chinese people of Sichuan, at the foot of the Tibetan Plateau, who were reported by Brian Houghton Hodgson in 1874.
According to Hodgson, who thought the Gyami descended from a Chinese military outpost, the Chinese considered the Gyami to be Hsifan, suggesting that they did not recognize them as Chinese and that they did not use Chinese script. Victor Mair notes that what little is recorded of their speech indicates a degree of assimilation to local languages, but that it is clearly a variety of Mandarin.