According to a report in the New York Times, Muslims living in Xinjiang must abide by a stringent set of rules in their religious practice:
To be a practicing Muslim in the vast autonomous region of northwestern China called Xinjiang is to live under an intricate series of laws and regulations intended to control the spread and practice of Islam, the predominant religion among the Uighurs, a Turkic people uneasy with Chinese rule.
The edicts touch on every facet of a Muslim’s way of life. Official versions of the Koran are the only legal ones. Imams may not teach the Koran in private, and studying Arabic is allowed only at special government schools.
Two of Islam’s five pillars — the sacred fasting month of Ramadan and the pilgrimage to Mecca called the hajj — are also carefully controlled. Students and government workers are compelled to eat during Ramadan, and the passports of Uighurs have been confiscated across Xinjiang to force them to join government-run hajj tours rather than travel illegally to Mecca on their own.