There's historically marginalized people everywhere, if you go back far enough in time everyone was and everyone has. Those "natives" oppressed other natives at some point (unless you believe in that wholesome native tribe - Comanches, Tibetans, Hawaiians - they weren't very nice to their neighbors) so do those ancestors get to claim the land? If you do keep giving people what is 'rightfully' theirs by going back further and further, then you get into situations like Africa where tribal wars and slavery have been marginalizing the country for centuries, long before a white man ever put a flag in the ground.
To give people like American "Indians", Hawaiians a pittance because someone feels bad about their ancestors' actions is marginalizing them even further. To say they were 'wholesome', peaceful or somehow better than anyone else is racist, it's taking away their humanity, there was good and evil as well in their history, to ignore it is just hiding their rich history of wars, peace, settlement, nomadic life, trade and treaties.
Is it "their" land (as in they own it currently and it was in the process of being taken by the government)? No? If they want it back, they should conquer it and deal with the consequences of trying to stake claim to another nation's property.