Well, we could at least get a Nepalese civ to represent the Himalayan area in general, since Tibet would indeed probably cause all sorts of problems for the China market.
I. Have been saying this. FOREVER. I have have been suggesting a Nepali Civ so long, one of the main reasons I was so disappointed with Carthage in Civ 5 was that its mountaineering ability effectively sealed Nepal's doom as it was obvious no other side would get such a power. It's been one of my favorite darkhorse civs for a very long time along with the Olmec, Nigeria, and Wallachia (Romania/Transylvania). Something like:
Leader: Prithvi Narayan Shah
Capital: Kathmandu (while he wasn't born there nor did his reign start there he moved the capital to Kathmandu to make it more centralized and defensible early in his reign)
Colors: Red borders with Blue interior (I know the Nepali flag is opposite this but Norway and Persia already took Blue on Red. So Red on Blue it is)
Leader Ability: Divya Upadesh- +1 culture and faith from hill tiles adjacent to city centers. Land combat units have a +3 combat bonus when fighting on hill tiles and a +3 combat bonus when fighting adjacent to mountains. (these bonuses do stack)
Leader Agenda: First Gorkha King- Likes to have well defended cities. Respects civs with large defensive armies (positioned around their own cities). Dislikes civs that position their troops on Nepali borders. (his whole reason for unifying Nepal was out of fear of English Imperialism and wanting a strong centralized government and army in case the English attempted to extend their reach out of India and into Nepal)
Civilization Ability: Sherpa- +1 adjacency bonus for all districts located next to a mountain. Nepali trade routes may move through and construct roads on mountain tiles, and generate 1 extra gold for each mountain tile passed through on their route. Land units may move across mountain roads but suffer -35 damage if they end their turn on a mountain tile.
Unique Unit: Gurkha- Unique unit unlocked at rifling with comparable combat strength to Guarde Imperiale and Redcoat. Starts with the unique "Tenacity" promotion which allows them to attack an adjacent enemy unit even if they do not have the movement points required. (Note this would not give them an extra attack. It just means that even if an attack would require them to expend more movement points then they have left they may still commence an attack that turn, at which point they'd be expended for the rest of the turn like normal)
Unique Infrastructure: Himalayan Monastery (still trying to come up with a better name. I was just going to call it Monastery until they actually added that as a building Grrr!)- Replaces Temple. Generates tourism equal to half the faith generated by the holy site in which the Himalayan Monastery is located.
Theme: Not sure yet.
Obviously these are just spitball ideas and would require proper balancing and testing I'm just throwing this out there as a proof of concept that there's enough history and mechanics there to build a civilization around.