China has blamed Uyghur separatists for a number of attacks in recent years, including one on a coalmine in September 2015, in which 50 people were killed. But exiled groups and human rights activists say the government’s repressive religious policies and economic marginalization are provoking the unrest. “Chinese authorities have given no credible reason for taking away people’s passports, violating their right to freedom of movement,” Sophie Richardson, China Director for Human Rights Watch said in a statement.

“Doing so across an entire region is a form of collective punishment and fuels resentment toward the government in a region where tensions are high.”