Because they all had a common enemy ( the evil axis, and the soviets) and they had to work hard together and sacrifice a lot to defeat them.
If you are referring to the people Christopher Columbus found in America and incorrectly named them Indians (because he thought he had arrived in India), then the correct answer is Native Americans.
the theme of Antigone is the conflict between feeling and thinking
So its basically [I think] saying if you were to treat a dog with pity and show no shelter of compassion then you will also treat humans the same way.