Probably derived from their ancestors’ slave names. George Washington had slaves with names: Muclus, Dolshy, Alla, Leanthe, Oney, Sucky (don’t say it!), Sacky, Alce, Urinah, Breechy, Heuky, Savary, Isrias, Fomison, Sall Twine, Eneas, Hellam and Neptune.
Most of the names were given by the white slave owners, along with the spellings. It’s a fascinating subject for study and appears to have nearly unlimited subject matter.
I looked up the Founder’s List for the slave names and have to admit, you did not need a sarc tag. The other thing I noticed is that Washington’s slaves must have been treated a lot better than most other slaves, they were really long lived. They were living longer than the average age of white slave owners for that period.