What were the most evil nations in history?

[Stranger in a strange land]

Some thoughts:

- North Korea belongs on the list, given that it basically is Oceania from 1984 in real life.

- Even the Stalin-era USSR wasn't as bad as Democratic Kampuchea

- The British Empire may have been evil, but it was nowhere near as evil as the Nazis, and the implication that you would have rooted for the Nazis in the North African theatre of World War II but for the Soviets on the Eastern front would be disturbing if it weren't so mind-boggling that I can't quite wrap my head around it. The British Empire really wasn't any worse than any of the other contemporary European colonial empires, and they were actually better in some respects. What makes it so much worse than Belgium under Leopold II, for instance? For that matter, what makes it worse than the Roman Empire? The Romans certainly weren't above committing genocide against troublesome conquered peoples, and gave us the phrase, "make a desert and call it peace."