Let's talk about history

Today I just started more extensive reading on Tibetan pastoralism. The direction I am looking at is pastoral system's evolution in Tibet since its earliest establishment to present day. On JSTOR along I can find several hundred articles on Tibet's pastoral history, which are often interwoven with politics, superstructures and environmental and ethnography causes. Materials I read today are mostly focusing on 20th Century. This gives people an impression that most changes to Tibetan pastoralism have taken place in the 20th Century. This may not be far from the truth. But I still wonder what happened in the 1,000 years before this century. From common sense, there should be something changed during the period. The western researchers tend to illustrate Tibet traditional pastoral system as a desirable system which achieved equilibrium and (to some extent) sustainability in a harsh environment. However, is it necessarily good for all people? In the traditional system there are people mistreated and discriminated, who led misrable life in that system. Do we need to sacrifice them in order to restore the traditional system and achieve sustainability without equity?