Not all the white slaves in North America were indentured servants.
I descend from one of the first indentured servants at Plymouth, 1620, Edward Doty.
I am related to cousins and great aunts and uncles who were captured by Indians in Maine, Vermont, New Hampshire and Massachusetts, marched up to Quebec and sold as slaves to the French.
The Indians kept a few to be their own slaves, and adopted the children into their tribes.
Some were ransomed back by relatives, some chose to remain in Canada, the owners of some refused the ransom and kept them.
Good point; this is known history, a good addition here. The Last of the Mohicans