I recently read The British Invasion of Tibet, 1903. Colonel FE Younghusband of the Indian Army is sent to Tibet to settle a border dispute. After a 6 month wait with the Tibetan monks--mainly the Lhasa big monastery monks and the Dalai Lama--obfuscating and obstructing every overture made, the British move north into Tibet. They fight one battle against 2000 Tibetans armed mostly with swords and matchlocks, with a few Russian breechloaders at a town called Guru. It was an interesting read and if you don't want to follow actual history, it would make for a good campaign. The British had 2 7 pounder guns and some maxim machine guns.
Younghusband attributes the Tibetan stubbornness to the monks' wanting to maintain their priestly power over the population.