Human Barbarians
There are many different styles of human barbarians. The barbarians still living in the civilized human lands of Sapientium, are pretty much Celtic/Gaelic types, with some Norse-like in the far North lands of that kingdom.
There are jungle-style barbarians, Polynesian-style, African-tribal-style, Mongolian style, Native American style, and just about any other culture that "more civilized" type cultures would call "barbarian", though that is too over broad an example.
The Sapientium barbarians have resisted learning the Latin tongue, and fought the centuries of Elven occupation. They hide in caves and small woods (they can't hide in larger woods because the wood elves generally control those). They have a tentative peace with King Arthur's reign, he won't sent troops to hunt them down, if they won't raid the villagers.