Weren't there instances of enslaved children being "on display" as "possessions" of the wealthy in Elizabethan England? I seem to recall seeing images of such children being used as footstools in England (but that may have been later than Elizabeth's time). My recollection of what I read decades ago was that such were regarded as a status symbol (denoting wealth), and that when the children grew too old to be "pretty" they were discarded.
If I am correct in my recollections, it went back much earlier than the late 1700s.
Either way, there should be a category for these people.