With any POD(s) in the 1900s, how would Manchuria, Tibet, Xinjiang and Mongolia succeed in getting, and retaining, its independence from China?
Jiang Jieshi doesn't send soldiers into Manchuria post-1945, and full-scale civil war is staved off with the help of the Soviet government for negotiations. Manchuria remains independent as a Communist puppet state (which of course insists that it's the real China.)
This is pretty much the only way you can get long-lasting Manchurian independence.
Soviets send more aid to Second East Turkestan Republic, and peace deal between Communist Manchuria/RoC preserves its independence in a somewhat expanded form from IOTL as a Soviet puppet. It's small and only takes up the northern three or so districts of Xinjiang, but is still independence for the Uighur Turks.
Republic of China is afraid of forcibly incorporating Tibet, as that would potentially lead to loss of necessary international support from the West and upset a delicate unstable situation. By the time their internal situation is semi-stable, Tibet is essentially an Indian puppet, and India has the edge over the deeply corrupt, unpopular, and decaying Republic of China in terms of power projection.
There, done.