Pretty much every history book I've ever read. Look, maybe I picked the wrong particular group of people, because I can sense you're about to launch into some crazy argument that modern day Palestinians are the direct descendents of the Canaanites (which they couldn't possibly be). My point in using that example is if you dig deep enough, there's always a people that existed on that chunk of turf prior to the ones who claim it, ad nauseum. Let's pick another place that's seen some rotation:

Does England belong to the Normans? The Angles? The Saxons? The Romans? The Celts? The Bretans? Maybe there were people there before that? My point is there is almost a limitless timeline back into the past of displaced owners. Where does one stop and say 'these are the original, rightful owners' ?