Board Thread:Lore Discussion/@comment-27037725-20160512105922/@comment-25078513-20161104054853

Not an expert but as mentioned, most nations and tribes, as in real life, probably practiced slavery at some point. Morrowind stood out because it lasted long after it was banned in the larger empire, was a big part of Dunmer society, and they had a specific history of enslaving Argonians and Khajiit.

There is an article on this wiki about slavery in Tamerial here.

Notably, the elven Ayleids enslaved humans until they rebelled. As mentioned, some Argonians did keep slaves of their own kind, probably the result of inter tribal wars, although due to the demands of the Dunmer the Archein  became notorious for enslaving and selling their own people.

It's worth noting their are different degrees of slavery and indentured servanthood, and that historically, many civilazations treated slavery as a typical practice for punishing a conquered or rebelling city. Tiber Septim, as mentioned, did this with certain Bretons after defeating them.

Again, it may be that slavery was more treated as a form of punishing or dealing with conquered peoples or rebels vs the situation in Morrowind where it was a longstanding instituion where they actively sought out Argonians and Khajiit for their plantation labor.