After having a little google and wikipedia on this group two things
1) With such an obscure group, I would recommend providing some resources and information.
2) The best bet for this society is if they find and tap into the giant aquifer beneath the Tarim Basin - yes, it is very carbon-rich, which may be bad for the atmosphere, and obscenely salty - but if the salt can be taken, and shipped out as a good, and the remaining water used? You could seriously transform the Tarim basin.
However, the easiest? These people need to be able to take advantage of a water source, perhaps one of the high lakes nearby, and build a series of settlements there - the mountains are near-impenetrable, and would certainly provide them with shelter, and defense (even if they are cold).
That combined with the trade could be a good start, but they're in the worst position regarding steppe tribes. Unless they have a series steppe presence, or can do so - perhaps leaving the Tarim Basin in the process, then maybe. But that'd still be a shot in the dark.