疏附县(Kona Sheher)where Riot happens, is a county of Kashgar, one of the poorest part of Xinjiang. Kona Sheher has a population of 360,000, 350,000 of which are Uyghur, more than 97% are Uyghur.
In xinjiang, the richest part is always Han dominant, the poorest part is always Uyghur and minority dominant. Just like Karamay city, Han people account for more than 81%, it GDP per capital is nearly $20,000 USD in 2011. And Shihezi city, Han people is more than 95%, it's GDP per capital is $8,366 USD. While in Kashgar, GDP per capital is only $1,600, Uyghur and minority is more than 80%~90%.
Why riots happen? Poor. They cannot handle it. In China, Han is always tolerating them, give them financial aid, superior treatment over other Hans, like extra point bonus(or points deduction) in College Entrance Examination. But riots happen all the way.