Because in many cases we signed legally binding treaties with what were sovereign people at the time (and ostensibly are today but in practice not actually). We

Because in many cases we signed legally binding treaties with what were sovereign people at the time (and ostensibly are today but in practice not actually). We have either used loopholes or outright reneged on the treaties to further take their land away. I don't know if the time passed is relevant, when we pass treaties and sign agreements in general they have to mean something if we intend to be a nation of laws.