Western Regions

In 138 BC, the Emperor Wu of Western Han dynasty sent a diplomatic envoy represented by Zhang Qian to Xiyu in an effort to contact and make alliance with Yuezhi to mitigate the threat posed by the Xiongnu confederation.

Although Zhang was captured and imprisoned by Xiongnu for ten years, and the mission was eventually unsuccessful (due to Yuezhi no longer wanted to return to the east), his travels into the various states in the west served as a precursor for the long history between China and Central Asia.

The region became significant in later centuries as a cultural conduit between East Asia, the Indian subcontinent, the Muslim world and Europe, such as during the period of the Mongol Empire.

[2] Xiyu tudi renwu lüe (Brief Records of the Lands and Peoples in the Western Regions), a chapter in the Gazetteer of Shaanxi compiled by Ming dynasty Chinese scholar Ma Li in 1542, documents a route leading from the Jiayu Pass, China's northwestern outpost, to the Ottoman Empire capital Istanbul and geography and economy of the places along the route.

By the early twentieth century, the Russia Empire (and then its successor state the Soviet Union) controlled most of the regions to the west of Xinjiang.