Xinjiang is an autonomous region (Xinjiang Uyghur Autonomous Region) of China.

Xinjiang is a large, sparsely populated area, spanning over 1.6 million k㎡ (comparable in size to Iran or Western Europe), which takes up about one sixth of the country's territory. Xinjiang borders the Tibet Autonomous Region and India's Leh District to the south and Qinghai and Gansu provinces to the southeast, Mongolia to the east, Russia to the north, and Kazakhstan, Kyrgyzstan, Tajikistan, Afghanistan, Pakistan and India to the west. It administers most of Aksai Chin, a territory formally part of Kashmir's Ladakh region over which India has claimed sovereignty since 1962.

The east-west chain of the Tian Shan Mountains separate Dzungaria in the north from the Tarim Basin in the south. Dzungaria is dry steppe. The Tarim Basin is desert surrounded by oases. In the east is the Turpan Depression. In the west, the Tian Shan split, forming the Ili River valley.

History
According to J.P. Mallory, the Chinese sources describe the existence of "white people with long hair" or the Bai people in the Shan Hai Jing, who lived beyond their northwestern border.

The well-preserved Tarim mummies with Caucasoid features, often with reddish or blond hair, today displayed at the Urumqi Museum and dated to the 3rd century BC, have been found in precisely the same area of the Tarim Basin. Various nomadic tribes, such as the Yuezhi were part of the large migration of Indo-European speaking peoples who were settled in eastern Central Asia (possibly as far as Gansu) at that time. The Ordos culture situated at northern China east of the Yuezhi, are another example.

Nomadic cultures such as the Yuezhi are documented in the area of Xinjiang where the first known reference to the Yuezhi was made in 645 BC by the Chinese Guan Zhong in his Guanzi(Guanzi Essays: 73: 78: 80: 81). He described the Yuzhi, or Niuzhi, as a people from the north-west who supplied jade to the Chinese from the nearby mountains of Yuzhi at Gansu. The supply of jade from the Tarim Basin from ancient times is indeed well documented archaeologically: "It is well known that ancient Chinese rulers had a strong attachment to jade. All of the jade items excavated from the tomb of Fuhao of the Shang dynasty, more than 750 pieces, were from Khotan in modern Xinjiang. As early as the mid-first millennium BC the Yuezhi engaged in the jade trade, of which the major consumers were the rulers of agricultural China.".

The nomadic tribes of the Yuezhi are also documented in detail in Chinese historical accounts, in particular the 2nd-1st century BC "Records of the Great Historian", or Shiji, by Sima Qian, which state that they "were flourishing" but regularly in conflict with the neighboring tribe of the Xiongnu to the northeast.

Tang Dynasty and the Khanates
The Tang Dynasty was established in 618, and would prove to be one of the most expansionist dynasties in Chinese history. Starting from the 620's and 630's, Tang China conducted a series of expeditions against the Turks, eventually forcing the surrender of the western Turks in 657. Xinjiang was placed under the Anxi Protectorate ("Protectorate Pacifying the West"). The protectorate did not outlast the decline of Tang China in the 8th century. During the devastating Anshi Rebellion, Tibet invaded Tang China on a wide front from Xinjiang to Yunnan, occupied the Tang capital Chang'an in 763 for 16 days, and taking control of southern Xinjiang by the end of the century. At the same time, the Uyghur Khaganate took control of northern Xinjiang, as well as much of the rest of Central Asia, including Mongolia.

 
Blue-eyed Central Asian (Tocharian?) and East-Asian Buddhist monks, Bezeklik, Eastern Tarim Basin, 9th-10th century. Both Tibet and the Uyghur Khaganate declined in the mid-9th century. The Kara-Khanid Khanate, which arose from a confederation of Turkic tribes scattered after the destruction of the Uyghur empire, took control of western Xinjiang in the 10th century and the 11th century. Meanwhile, after the Uyghur khanate in Mongolia had been smashed by the Kirghiz, branches of the Uyghurs established themselves in the area around today's Turpan and Urumchi in 840. This Uyghur state would remain in eastern Xinjiang until the 13th century, though it would be subject to various overlords during that time. Some scholars have argued, that the Kara-Khanids were likewise "Uyghurs," as some of the components in the Kara-Khanid federation were likewise from the ruling clans of the Uyghur empire. The Kara-Khanids converted to Islam, whereas the Uyghur state in eastern Xinjiang remained Manicheaean, while tolerating Buddhism and Christianity.

In 1132, remnants of the Khitan Empire from Manchuria entered Xinjiang, fleeing the onslaught of the Jurchens into north China. They established an exile regime, the Kara-Khitan Khanate, which became overlord over both Kara-Khanid-held and Uyghur-held parts of the Tarim Basin for the next century.

Arrival of the Mongols
After Genghis Khan had unified Mongolia and began his advance west, the Uyghur state in the Turpan-Urumchi area offered its allegiance to the Mongols in 1209, contributing taxes and troops to the Mongol imperial effort. In return, the Uyghur rulers retained control of their kingdom. By contrast, Genghis Khan's Mongol Empire conquered the Kara-Khitan in 1218. Because the Kara-Khitan had persecuted Islam, the Mongols were met as liberators in the Kashgar area. During the civil war of the Mongol Empire, the Empire of the Great Khan (Yuan Dynasty) vied for rule with the Chagatai Khanate in the area. After the break-up of the Mongol Empire into smaller khanates the region fractured and was ruled by various different Persianized Mongol Khans simultaneously, including the ones of Mogholistan (with the assistance of the local Dughlat Emirs), Uigurstan (later Turpan) and Kashgaria. These leaders engaged in numerous wars with each other and both the Timurids of Transoxania to the West and the Western Mongols to the East, the successor Chagatai regime based in Mongolia and in China. Although there were high points in Persian culture reached (e.g. the Dughlat historian Hamid-mirza), succession crises and internal divisions (Kashgaria split in two for centuries) meant that this region almost completely fades from the history books during the 16th and 17th centuries.[16] In the 17th century, the Mongolian Dzungars established an empire over much of the region.

Dzungar Empire
Dzungar (also Jungar, Zunghar or Zungar) is the collective identity of several Oirat tribes that formed and maintained one of the last nomadic empires. The Dzungar Khanate covered the area called Dzungaria and stretched from the west end of the Great Wall of China to present-day eastern Kazakhstan, and from present-day northern Kyrgyzstan to southern Siberia (most of this area is renamed to Xinjiang after fall the Dzungar Empire). It existed from the early 17th century to the mid-18th century.

Qing Dynasty
Yaqub Beg was a Tajik adventurer who became head of the kingdom of Kashgaria.The Qing, established by the Manchus in China, gained control over eastern Xinjiang as a result of a long struggle with the Zunghars (Dzungars) that began in the seventeenth century. In 1755, the Qing attacked Ghulja, and captured the Zunghar khan. Over the next two years, the Manchus and Mongol armies of the Qing destroyed the remnants of the Zunghar khanate.

The Dzungars were deliberately exterminated in a brutal campaign of ethnic genocide. One writer, Wei Yuan, described the resulting desolation in what is now northern Xinjiang as: "an empty plain for a thousand li, with no trace of man." It has been estimated that more than a million people were slaughtered, and it took generations for it to recover.

By the mid-19th century, the Russian Empire was encroaching upon Qing China along its entire northern frontier. The Opium Wars and Taiping and other rebellion's in China proper had severely restricted the dynasty's ability to maintain its garrisons in distant Xinjiang. In 1864 both Chinese Muslims (Hui) and Uyghurs rebelled in Xinjiang cities, following an on-going Chinese Muslim Rebellion in Gansu and Shaanxi provinces further east. Because all of the non-Muslim population in Xinjiang were regarded as infidels and enemies to be exterminated, the rebellion resulted in incredible cruelties whenever the towns held by the Qing force were taken. In 1865, Yaqub Beg, a warlord from the neighbouring Khanate of Kokand, entered Xinjiang via Kashgar, and conquered nearly all of Xinjiang over the next six years. In 1871, Russia took advantage of the chaotic situation and seized the rich Ili River valley, including Gulja. By then, Qing China held onto only a few strongholds, including Tacheng.

The autonomous region of the PRC was established on 1 October 1955, replacing the province.