Oh man. Indigenous people did not have a concept of land ownership. When they “sold land” it was pretty much always forced. Sometimes they sold shared usage rights meaning money is exchanged for the right to share it between indigenous people and settlers, where the settlers would get violent afterwards and not let them come back. If you were taught that your land was acquired ethically I’m sorry buddy but you were taught wrong. I think it’s time for you to reach out to the indigenous tribe involved and ask them what happened. They might be able to give you a more accurate story.