They don’t have to, statutes of limitations.
The white people called them blood thirsty, godless savages among other things and decided to tame them with guns and bibles, put them in concentration camps "for their own protection" while they took their lands and opened them up to white settlers. Now here is the difference: If indeed the Indians were godless blood thirsty savages and killing their neighbors for land and dominance, that was a way of life that they always knew WHEREAS the White man was civilized , had God and supposedly a moral civilization. The conclusion to me is the White sin was a thousand times worse than what the Indians have always done in time immemorial.