The American settlement belongs to the European descendents of those that established the state in the Eastern parts of America (and gave the previous residents the right to either assimilate to that state with equal rights or keep tribal ties on reservations)

You "could argue" that the South-West part of America should belong to Natives/Mexicans based on the fact that there was a noteworthy presence of farming and populated agricultural development there, but we can only have that discussion if and when the original european-american nation is recognized

Also, the descendents of Native Americans DO NOT BENEFIT FROM MORE MIGRATION as their lives ALSO get worse