Ridzwan Abdul Rahman
Self employed (2000–present)7mo
How and why did the Qing Dynasty conquer Xinjiang?
If your intention is to claim that Xinjiang only came under Chinese rule during the Qing Dynasty, here is some history for you:

The nomadic Xiongnu people used to control the Xinjiang region but they used to attack the Central region of China under the Qin and later the Han dynasties.

Emperor Wudi of the Han dynasty then adopted a military response to the Xiongnu. In 60 BC, the Xiongnu king who ruled the areas north of the Eastern Tianshan Mountains surrendered to the Han government, which thereby incorporated Xinjiang into Han's territory. In the same year, Xinjiang's Frontier Command was established to exercise military and political administration over Xinjiang. Xinjiang was then called the "Western Regions".

In 123 AD, during the Eastern Han Dynasty, the Western Regions Frontier Command was replaced by the Western Regions Garrison Command, which continued to administer the Western Regions.

In 220 AD, with the end of the Han Dynasty, China became the three kingdoms of Wei, Shu, and Wu for 60 years. This was followed by the Jin dynasty in 280 AD.

The Kingdom of Wei of the Three Kingdoms period adopted the Han system, stationing a garrison commander to rule the Western Regions. The Western Jin Dynasty stationed a garrison commander and a governor to exercise military and political administration over the Western Regions. In the Three Kingdoms period and the Jin Dynasty, the Xiongnu, Xianbei, Dingling, and Wuhuan in northern China moved inland and finally integrated with the Han ethnic group.

In 327, the Former Liang regime spread the system of prefectures and counties to the Western Regions and set up the Gaochang Prefecture in the Turpan Basin.

The year 460 AD was the first known appearance of the Uyghurs. From 460 AD to 640 AD, the Uighur community of Gaochang, centered in the Turpan Basin and with the Han people as the main population, was ruled successively by the Kan, Zhang, Ma, and Qu families.

So there you have it. The Uyghurs migrated to Xinjiang long after China had control over the region.

Coming back to the question of why the Qing dynasty took control of Xinjiang, it is because Xinjiang had belonged to China for a long time.

At that time, Xinjiang was ruled by the Dzungars who exploited the Uyghurs economically. The Uighurs were forced with multiple taxes by the Dzungars which they did not even have the ability to pay. They included water conservancy tax, draught animal tax, fruit tax, poll tax, land tax, tress and grass tax, gold and silver tax, and trade tax.

The Dzungars extracted 700 taels of gold, and also extracted cotton, copper, and cloth, from the six regions of Keriya, Kashgar, Khotan, Kucha, Yarkand, and Aksu (as stated by Russian topographer Yakoff Filisoff).

The Dzungars extracted over 50% of the wheat harvests of Muslims according to Qi-yi-shi (Chun Yuan), 30-40% of the wheat harvests of Muslims according to the Xiyu tuzhi, which labelled the tax as "plunder" of the Muslims.

The Dzungars also extorted extra taxes on cotton, silver, gold, and traded goods from the Muslims besides making them pay the official tax.

"Wine, meat, and women" and "a parting gift" were forcibly extracted from the Uighurs daily by the Dzungars who went to physically gather the taxes from the Uighur Muslims, and if they were dissatisfied with what they received, they would rape women, and loot and steal property and livestock.

Gold necklaces, diamonds, pearls, and precious stones from India were extracted from the Uighurs under Dāniyāl Khoja by Tsewang Rabtan when his daughter was getting married.

By defeating the Dzungars and taking control over Xinjiang again, the Qing dynasty freed the Uyghurs from the cruelty of the Dzungars.