Europeans enslaved enormous numbers of native Americans. So many, that some activists in the American Indian Movement claim more American Indians were enslaved than the number of African slaves were imported to the Americas. They may be biased and their documentation may not be complete, but there are three facts that do back up or support their claims.
After the Pequot and King Philips war in the early days of the New England colony, more than 60,000 native American slaves were exported to the West Indies. Between 1670 and 1720 more native American slaves were exported from Charleston South Carolina than African slaves were imported through Charleston South Carolina. The Catawba nation in North and South Carolina quickly established close relations with the English colonists of the Carolina colony and engaged in massive slaving raids against their neighbors to the west.
Sources: "The Indians' New World: Catawbas and Their Neighbors, From European Contact Through the Era of Removal" by J.H. Merrell (1989)
http://www.gilderlehrman.org/history-by-era/origins-slavery/essays/indian-slavery-americas by Allan Gallay
http://www.history.com/topics/native-american-history/king-philips-war