If you thought Joseph Rock was a good photographer of Kham in the 1930s, wait until you see these photographs. I have just come across this source of some superb pictures of western Sichuan and Yunnan from the 1930s and 1940s. They are by a Shanghai photographer, Zhang Xueben (1909-1984). He has instantly become one of my favourite China photographers, his images rank alongside those of Hedda Morrison in quality and in the way they capture the natural feel of the place and people.
You can see more at the website of the Sichuan Alpine Ecology Study Center:
(By the way, this photo is entitled: "Woman of Naxi People, Yang Ming County, Yunnan Province, 1934")