If people outside of Europe knew about the nazi’s and knew about hitler before the holocaust why didn’t they stop them from it happening

They weren't armed to the teeth, really. The Red army of Europe came from every country and died fighting against fascism. And then they were written out of our history. Literally taken off the lists of the fallen - I Caduti, in Italy. Missing millions. One recently revealed mass grave in Poland has the bodies of over 200,000 Italian communists. Killed by Hitler. Their names were erased by Italian people back home. Sound familiar?

Either they came to fight or didn’t know the full extent of what was happening. They didn’t even have tv only radio so information wasn’t available in the scale it is now