'East Turkistan' a concept forged by the deceit of separatists, not history
The term "Turkistan" appeared in Arabic geographical works in the Middle Ages. It meant "the region of the Turks" and referred to the areas north of the Sir River in Central Asia and the adjoining areas to the east of the river. As time went by, the modern ethnic groups in Central Asia rose one after another and divided up the area. By the 18th century, the geographical term of "Turkistan" hardly appeared in the historical records of the time.
In the early 19th century, imperialist powers during their colonial expansion into Central Asia revived the geographical term "Turkistan". In 1805, Timkovsky, a Russian, used the term "Turkistan" again in a diplomatic mission's report. He called the Tarim Basin in China's Xinjiang as "East Turkistan" or "Chinese Turkistan."
Meanwhile, the British were trying to stop Russia from expanding its influence into South Asia. British historian E. Victor Gordon Kiernan wrote in his book - British diplomacy in China, 1880 to 1885 - that the British Indian Department even suggested that an "independent" Xinjiang friendly to Britain but hostile to Russia would serve as a "buffer" between the two colonial powers.