I'm sorry blam, I would respectfully disagree with the theory that Caucasians originated from what is now part of Western China. Caucasians would have arisen from the swathe of land from the Black sea to the Eastern edges of the steppes in Central Asia, but any finds in the Gobi or beyond would have been just forays or foraging parties.
I'm not firmly committed to this idea. I am prepared to see some old assumptions about origins fall though.