Starting with historical backgorund could be interesting.

2000-2500 years ago Turks used to live in that area (Middle Asia region, which belongs today China, Mogholistan, etc). But in consequence of some factors (like drought, etc) they had to move west. Some decided to go North and formed Huns (ancestors of Hungary, Finland and Bulgaria); some decided to go direct West and formed Seljuks, Ottomans and finally today's Turkey, Azerbaijan and Cyprus; some decided to stay in that region and formed today's Turkmenistan, Kazhakistan, Uzbekistan, Kirghizistan. These are independend ones. East Turkestan is the one of the many autonom regions.
Today -as far as I know- they are not allowed to have more than 2 children, jails in the area is totally under awful circumstances (United Nations Human Rights Comitee says this) and in order to reduce their population density they bring people who lives out of the area to there. Actually I know much more things but I have no evidence so I don't write them down.