What a weird question, does that include Chiang Kai-shek? or limited to the "communist" party?

You don't remember the '79 Vietnam War? The Chinese one where they invaded North Vietnam with thousands tanks and 10s of thousands on both sides died over the course of months. Relations normalized in '91.

https://en.wikipedia.org/wiki/Sino-Vietnamese_War

China supported the Khmer Rouge, maybe Pol Pot is memorable?