I'm trying to decide if World War II was the only event in human history that affected virtually all humanity (the except being uncontacted tribes and the like). I have a few ideas of places that might have been virtually unaffected.

Western South America- I know Argentina and Brazil were involved in the war, but what about places like Chile or Peru

Central America- What about a country like Costa Rica? I think I read that German naval units were active in the Caribbean, but did they ever make it to mainland Central America?

Any help guys?