Why Mexican try to clam native without claim native heritage without tribal doentation.?

im not here to start something but I cant figuer out why so many mexican try to clam native american heritage,without any tribal doent most native american in this country live in tribal.I can tell you that their where no mexican leaving in the southwest or west and their are proof their was none,why are they try to take their land this is native american land not their I know alot of native ameircan feel the same why native and mexican are different people their not the same need to stand up say enough where your tribal doent to show proof that their belong ,to the native tribal all they do is ***** and complain about some land that dosent belong to them the first place they mine well give back spain their land mexico was spain before learn your history before you try to claim something I know more stuff then you.Do you really know native history mine girlfriend is native she tought me alot about here people and most native are angry because they feel like they trying to claim their heritage which they nave no proof they belong to the native and why no meixcan is not living in indian reservations their most native live in.