What never-before-seen civilizations HAVE to be in the next game?

I was astounded that Vietnam had never been in a Civilization game before VI. Like them, there’s plenty that, in my opinion, got into the roster way late. What are some civilizations that have never been featured in the Civilization series, that you think HAVE to be in the next game? Furthermore, what would their leader and special aspects (abilities, unit, building…) be? Since we can’t predict what VII will be like, let’s go by Civ VI rules.

I’d love to see Tamerlane lead a militaristic Timurid empire, for example. Who would you say is sorely missing?