What’s a piece of hidden history from your country that you feel should be common knowledge?

We were never taught in school that the Soviet Union was run by communists under the Bolshevik regime. This regime resulted in genocide of Christians and other religions in an attempt to ethnically cleanse the country and remove religion entirely. Over 20m people were killed in this. Not sure why this was never taught to us.

I feel like there is a lot of hidden history with Native Americans that has not been in media, so their issues go unresolved and unnoticed.

The CIA and the FBI do not have clean hands in any sort of the word. I would love if the FOI act activated sooner and their matters to keep them in check.