First, its Uyghurs. Also, China is populated with 56 ethnics, and the CCP is mostly populated by the Han Ethnicity. Before the PRC's founding, the area of Xinjiang was governed and owned by the Russians. Then, the Xinjiang area's people, or the Uyghurs, had Anti-Han activities. The CCP obviously wanted to stop this, because Xinjiang is a confidential area, it is hard for a foreigner to enter. A lot of secret stuff is at Xinjiang, and if the Uyghurs part from China, that could mean a lot of information leaks. China is trying to stop this.