Many cultures in Aeons are still quite primitive, and in these the berserker power of the Barbarian is considered essential to their survival.
The races most likely to have barbarians are Gurathi, Torani, and Umani. The Gurathi prize the battle raging abilities of barbarians quite highly: their most celebrated warriors, the Keldak Drath, are battle-scarred elder female barbarians. For Torani, any force that helps them face the Blight is welcome; the tribes of Torani living in the subterrane closest to the Blight, and most desperate for help, do seek the dangerous help of barbarian rage. Umani tribes living close to nature have a lot of use for powerful warriors who don’t rely on heavy armor or esoteric disciplines.