In short order: Some uprisings that get omitted from the history curriculum in most American schools, a world war, an explosion of wealth inequality, a stock market crash and some economic stagnation, another world war, a period of some actually progressive politics, followed by a slow hollowing out and destruction of anything that previous period created, interspersed with some more wars, a couple of stock market crashes, more wars, present day.

The Russian Revolution, and the victory of the Communists in China against the robber baron side led by Chiang Kai Shek. The revolution was crushed almost everywhere else by the robber barons. Some countries made large concessions to the workers to help that stick, like the New Deal in the US and the reforms of the Labour government in Britain.

After that it gets complicated.