To the best of my knowledge, Native Americans do not have a history of enslaving others, not even those that were highly developed, not in the traditional sense of American slavery.
But African-Americans were found on every side of this land.
Those that came before the Mayflower traded with Indians, mixed with Indians and settled in various locations here in peace with native Americans.
Those who came on the Mayflower were originally indenture servants and settled here with other settlers—it is my understanding that they were few in number.
The enslaved Africans and the freed Africans, just like the poor serfs and the free poor whites, fought against the Native Americans with Whites.
When the enslavement of Blacks were full, Indians who mixed with Whites not only enslaved runaway Africans but also learned to see themselves as a different people and learned to enslaved their darker Indian brothers (e.g. Chickasaw, Choctow).
Other Indians helped runaway Africans and mixed with them as well.
There is no one Indian story. And there is no one African story in this land. At a given time, all Indians did not enslave Blacks. And at a given time, Blacks and Whites mixed wit various Indian tribes. And at a given time, Blacks and Whites warred against the Indians.
Of course I’m not expert on Indian history; this is just my understanding based on what I’ve read and heard here and there on the subject. A reliable and professionally written account has to be examined and written if it hasn’t already.