No I didn't mix it up, I included the Amish, could have included Romani, and specified that I was talking about geographically dispersed ethnicities in general.
Yes, some Jewish people have ties to what is Israel today, and no it really doesn't open a can of worms. I was very clear that displacing any group of people is wrong: Hence, the state of Israel should never have been created, but now that it exists, we need to figure out a solution that doesn't involve displacing any more people.
To answer the "how far back" etc: Quite simply put, everyone today (sans a couple hundred thousand stateless Palestinian refugees, and a few others) have some citizenship and live on some land. Nobody has the right to displace others to claim that they have "more" of a right to that land. Thus: If you have ties to some land, and someone else lives there, you're shit outta luck unless they want to negotiate with you. If, like the Kurds, your living in the place you have ties to, but don't have your own state, you have a decent case.
It really isn't that complicated: Don't displace/murder people. Two wrongs don't make a right.
It's true that a lot of peoples (maybe most?) today live in a place which they took by force from someone else, though you don't have to look far to find areas that are still inhabited by the first people that arrived there. Still, for a fair comparison you need to separate between those that took areas by force either from necessity (e.g. they were displaced themselves) or otherwise before any kind of international regulation existed.
You cannot compare a tribe or small kingdom taking land by force 2000 years ago to a modern state annexing land, just like you cannot compare the sacking of a city 1000 years ago to a modern genocide. The world has changed.