Where does it say that those who occupy land "first" (as if they could ever prove they were "first") own it forever?  No such natural law, it's just a nice-feeling made-up concept.  I say the guy who's on it now owns it.  (Anyway, I thought "ownership" of land was a concept indigenous folks don't believe exists so I'm surprised they don't correct Mr Trudeau when he says we are on their land.)