I feel like in most cases people should be able to keep their ancestors' land

To say most cases is bold, I believe that in [some] cases people should be able to keep their ancestors land. If they are natives to the area, they shouldn't be uprooted from their home. Though if a group's ancestors resided somewhere else long before their time, I don't believe they have a right to go to where their ancestors lived and claim it as their own, but I believe they should have a right to at least reside their if it will not bother the current society residing in the land.