Oh please. I challenge you to find any inhabited land on this planet that wasn't forcibly taken from someone at some point in the past. At best, you might find some remote islands where the current inhabitants are descended from the original settlers, but even there if you could magically look back in time you might find that one clan stole the land from some other clan after wiping them out in a war.

>don't for a moment think those rules are any more legitimate just because you say so.

The only thing that makes the rules legitimate is the ability to back up those rules with force.