For the last couple of days there have been serious race riots in Urumqi, the capital of the Xinjiang province of China, between the ruling Han Chinese and the Uighur natives. The Uighurs are a Turkic Central Asian people that speak a language closely related to Uzbek, but written in Arabic script. Like other Central Asians they are mostly Sunni Muslims. There is a fairly large Uighur population in Kyrgyzstan. Many of them are the descendants of refugees that fled to the Soviet Union during the Great Leap Forward and Cultural Revolution. The New York Times has a fairly good article on the recent clashes at the URL below.
This article from the Wall Street Journal provides the immediate background for the current violence between Chinese and Uighurs.