Hi, I am sure it is a mountain weasel or Altai weasel. The yellow-bellied weasel is far more dark in its back (at least in China), and is more-or-less a lowland forest species; on the other side, the mountain weasel is a typical highland species in China, and is also the most friendly weasel species in China, as there are many mountain weasel photos taken in Tibet and west Sichuan by Chinese photographers, thus I am pretty sure it is a mountain weasel.
I still believe this animal is far too dark to be an Altai weasel - none of the photographs I can find show an animal this dark, even in their darker summer colouration at which point they reach about this point:
There is another possibility, of course, which is that the two species might intergrade in this area - the yellow-bellied is little studied, so it might be possible.
Two people on the Birdforum thread with direct experience of mountain weasels in the wild (one also with experience with yellow-bellied weasels) say this is definitely a mountain weasel. So I'm going with them and baboon and putting it down as a mountain weasel.
A
amateur
It is without doubt the M.altaica. Actually, I think that you will not meet the M.khatiah where there is snow. Nice picture! The color of fur is change in seasons and individually too. The body size of M.altaica about how the ermine (M.erminea) or slightly more...
