It has been five years since rioting left almost 200 people dead in the far western Chinese city of Urumqi, in Xinjiang region.
The clashes were between migrant Han Chinese and ethnic Muslim Uighurs, who have decried continued violations of their rights as minorities.
Security has been tightened ahead of the anniversary, which coincided with Ramadan this year, and more than 400 people have been arrested.
Al Jazeera's Adrian Brown reports from Urumqi.
Source: Al Jazeera