I’ve been doing a bit of research on Central Asia and have come up with a few more detailed route possibilities. I would like to leave Russia and Kazakhstan out of the picture only because I am less interested in them than other countries, like Uzbekistan, and traveling, visas and lodging would be expensive. I don’t mind paying for a visa if I want to see a country, but I would hate to pay $100 to enter Kazakhstan just to run for the border.
Assuming the cheapest flight to Mongolia is through South Korea, I would like to fly from Mongolia to Turkmenistan. The research I’ve done so far tells me there are no flights between those two countries, but it may be possible to fly to Uzbekistan and definitely to Kazakhstan. I might have to fly on a tiny plane out of Western Mongolia. Then on through Turkmenistan, Uzbekistan, Kyrgistan to the Chinese border and Kashgar. From Kashgar I cam make my way to Golmud where the bus leaves for Lhasa.
If I can’t make flights from Mongolia work I could easily travel through China Westward to Urmqui. From there I can cross into Kazakhstan and head onward or I can go South within China to Kashgar and cross into Kyrgistan, although I would be backtracking on the way back into China. From there I could loop through Uzbekistan and Turkmenistan (or leave Turkmenistan out) and head through Tajikstan to Osh in Kyrgistan. From Osh I should be able to take the mountain pass into China and arrive in Kashgar.