If you're American and a bunch of native Americans said that the land your house is on belongs to them so you should fuck off or they'll kill you, I'm pretty sure you'd have an issue with that. Yes, once upon a time that land was theirs. A LONG TIME AGO. Many generations of Palestinians have lived in Palestine, so there really isn't a historic entitlement argument for Israelis to claim their land by, least of all the Law of Return that Israel has been peddling. Should people from Italy start claiming land all around the world, or the British or any other group of people whose ancesters once lived elsewhere? I'm half Irish so I'm entitled to someone's land in Ireland? It's completely ludicrous.