The region's vast 1.6 million square kilometres accounts for a sixth of China's territory and spans into Central Asia. It borders Afghanistan, the former Soviet republics of Tajikistan, Kyrgyzstan and Kazakhstan, as well as Russia to the north and the Pakistan and Indian-controlled parts of Kashmir to the south.
20 million, representing 47 ethnic groups. The largest group is the roughly nine million ethnic Uighurs - a Turkic-speaking central Asian people. But the number of Han Chinese in the region has risen from six per cent in 1949 to more than 40 per cent now. Critics say it is part of a policy of Han Chinese migration to dilute any nationalist tendencies.
China has long ruled Xinjiang in various degrees and re-established its control there in 1949 by crushing the short-lived state of East Turkestan that had emerged during the Chinese civil war. Xinjiang is one of China's five autonomous regions - a designation given by the government to recognise the status of an ethnic minority, though such regions are still tightly controlled by the state - along with Tibet. Uighurs say they have suffered under Chinese rule. Nationalist sentiment intensified in the 1990s after Soviet troops retreated from Afghanistan and three neighbouring Islamic Soviet republics gained independence.
Groups identifying themselves as the East Turkestan Islamic Movement (ETIM) and the Turkestan Islamic Party (TIP) want to establish an independent homeland for ethnic Uighurs. Some experts believe the two groups are one. The United States and the United Nations have listed ETIM as a terrorist organisation. Both Washington and Beijing say ETIM militants have received training and funding from Al-Qaeda, which some analysts dispute.