Some media outlets are calling this the deadliest unrest since Tiananmen Square in 1989. But the numbers from more recent clashes are difficult to verify. After the clashes in Tibet in 2008, China's official number of dead was less than two dozen, while Tibetan rights groups said 200 people died.
Xinjiang is a vast oil-rich desert in China's west. Almost half of Xinjiang's 20 million people are Uighurs, but the population of Urumqi is largely made up of Han Chinese immigrants. Ethnic tensions between the two groups are always high in Xinjiang. The Chinese government is wary of Uighurs and accuses them of trying to break away from China. And as in Tibet, the Uighurs have deep frustrations with the Communist Party's policies and the economic prosperity of the Han Chinese in the region.
The Associated Press contributed to the reporting of this story.