Native Americans had wars and conquered each other for millennia before white man came. It wasn't some unified utopia in the Americas like Pocahontas leads you to believe. It was a huge cycle of tribalism, conquering each other, and bloodshed.
So... because they were conquering each other first, a technologically superior entity isn't allowed to conquer them?
So... because they were conquering each other first, a technologically superior entity isn't allowed to conquer them?