I picked up the pdf when it first came out and have been thinking of how to integrate it into Hyperborea. My proposal – the Valley of the Five Fires is the Kimmerian ‘homeland’, and their legendary subterranean city of can be found therein.
Kimmerian roots trace their ancestors to the Caucasus Mountains of Old Earth. Their traditions say that they were driven into a foggy vale by their hated enemies, the Scythians, and overcome there by eldritch mists and a terrible piping. When the fog cleared, they found themselves in lost Hyperborea.
Over time, the Kimmerians spread across the Kimmerian Steppe and Fields of Vol, and inhabited a vast underground city – known as Krimmea to outsiders. When the Green Death ravaged Hyperborea, the underground city was closed off and the Kimmerian nomads were decimated. (They eventually lost the Fields of Vol to hybrid Kimmeri-Kelts.)
Now, there are five major groups occupying the Kimmerian Steppe – the Nergüi & Bolad Hordes, the Eagle Clan & Clan of the Worm, and the Mod Khöndii (or People of the Trees). The Five Fires of these tribes encircle the valley known as the Cradle of Man – home to the subterranean city, which now has limited relations with their above-ground kin. (There are also additional “animal tribes” and Kimmeri-Kelts who range further south into the Fields of Vol.)
Kimmerians in Astonishing ACKS:
Kimmerian PCs are assumed be members of the above-ground clans (or Kimmeri-Kelts) – their subterranean kin remain mysterious and inscrutable.
Classes & Backgrounds: I already have rules for Kimmerian Barbarians, masters of the composite bow. Kimmerian Scouts would be popular as well (my version of the Explorer class). The Shaman from the ACKS Player’s Companion can represent worshipers of the various animal tribes, and priests of Krimmr can be treated as Horse Shamans. Fighters and Thieves would also be common. Kimmerians favour mounted or cavalry-based background templates.
Armour & Weapons: Kimmerian armourers are highly regarded throughout Hyperborea. Highly-valued suits of gold-chased Kimmerian plate mail are manufactured in the subterranean city. Their aboveground cousins produce high-quality composite bows and various weapons which can be used on horseback.
Religion: The Kimmerians do not observe formal religion to the extent of other peoples – although they will at times pay homage to their deity, Krimmr (also called Krom), his name is often used as an expletive. Shamans of Kimmeria practice a form of animism that draws on the power of animal and nature spirits. They also hold respect for elders (the living) and ancestors (the dead). Kimmerians build stupas and ovoos – shrines and cairns – of throughout their lands at sites of religious significance.
Kimmeri-Kelts: By-blows of Kimmerian and Keltic mergers during the Dark Age that followed the Green Death, they combine traditions of both their parent races but are fiercely independent.