What's thought to be the worst violence in China for 20 years has seen 140 people die and 800 injured in Xinjiang in the west of the country.
The Chinese government says the violence was caused by a group of people called Uighurs.
Many Uighurs want the region where they live to become a new country that isn't part of China, but the Chinese government wants to keep control.
It's not clear what happened during the riots to kill so many people.
Journalists aren't able to report on whatever they want to in China, and the information about this riot has been provided by the government.
It is still unclear who died and why so many were killed.
Disagreements on details
The Chinese state media says protesters carried knives, bricks and batons, smashed cars and stores, and fought with security forces.
People speaking for the Uighurs said the protest was a peaceful one, and that police had fired on them.
They also said that many more people were killed and injured than the government is admitting.