I know Marxism/communism is supposed to create a union of the global proletariat that transcends nationalism, but has that ever actually got anywhere? Communist

I know Marxism/communism is supposed to create a union of the global proletariat that transcends nationalism, but has that ever actually got anywhere? Communist states seem to me just as fragmented and independent as any others. There was the eastern bloc dominated by the Soviet Union, sure, but that was straightforward imperialism enforced by military power. Similarly the Chinese hegemony over Tibet, Xinjiang etc seems straightforwardly imperialistic based on enthnographic domination. Marxist movements seem just as prone to factionalism and division as any other, if not more so.