1. Serfdom, tied to real property.
2. Chattel slavery, meaning you could sell and trade them like cattle. What is unique about the African Slave Trade was it relegated certain persons of dark melonation as secondary class citizens solely on the basis of skin color. Racial chattel slavery was created by Europeans to justify subjugation the persons sold as chattel.
Europeans had been subjected to serfdom and it existed to a smaller extent in the colonies. But when were Europeans subjected in large numbers to racial chattel slavery?