I just remembered now that you mention it, the Kumul Khanate was a Chagataid vassal Khanate under the Qing dynasty.
The wiki article is written badly (stunted sentences, no flow) but here it is. It also contains some inaccurate information (the opposite situation on settlements occured, most Han in Xinjiang settled in Dzungharia and not other parts of Xinjiang)
Kumul Khanate - Wikipedia, the free encyclopedia
Xinjiang also did not break free, the provincial administration was still in place. There was a massive three way war in the 1930s, with an attempt by some pan Turkist Uyghurs to declare an independent Republic but they were defeated by Hui soldiers. (Because of the violent pan Turkist language used by the Uyghurs they angered everyone who was not Turkic)
Kumul Rebellion - Wikipedia, the free encyclopedia
The Soviets backed another revolt under the Uyghur leader Ehmetjan Qasim but were forced to abandon it because of the communist victory in the Chinese civil war. Hui and Salar soldiers in the Chinese army fought against the Soviets and Uyghurs
Ili Rebellion - Wikipedia, the free encyclopedia
And before you ask me, I have no idea where the current Chagatai heirs live or if they even exist anymore.