The Carmanian Empire lasted from about 750 to about 1250. It was founded, as the stories go, by “atheist barbarians from the West”. For most of their history “atheist barbarians” were able to rule a polyglot empire that consisted of Pelandans, Dara Happans, and Theyalans. The ruling dynasty were skilled at respectfully acknowledging and using the gods of their subjects without submitting to any of them.
The leaders ruling dynasty often assigned autonomous appanages to members of their family. The most famous of these is when the Three Brothers divided the world. Nadar of Carmania was a great king (or shah) but had no sons. His daughter was married to a Dara Happan emperor (Sarenesh) and had three sons. When Nadar died, the sons were acclaimed rulers of both Carmania and Dara Happa. The senior son Sassacar (Kewetesh in Dara Happan sources) received Carmania and the title of King of Kings (Padishah), while the middle son Heredesh was given Dara Happa. The youngest son Verenmars received nothing except command of the armies fighting against the EWF – he conquered a kingdom of his own in Saird.
Of course the children of these brothers fought each other. Heredesh’s son Karsdevan proclaimed “I am not a Carmanian” and over the next few generations there were purges of Carmanian influences from Dara Happa, that eventually became three generations of dynastic conflict that only ended with the Invincible Golden Horde and the Dragonkill War.
The Carmanian dynasty retained their “atheist” reputation for their entire history, and the ruling dynasty were patrons of an Malkioni sect that had an elaborate dualist cosmology and adapted deities from its subject peoples into comprehensible forms. Individual members of the ruling dynasty were often eclectic in their practices, and histories show the cults of Yelm, Humakt, and even Storm Bull.
How does atheism work in a world with living, visible Gods? They are “atheists” in the sense that the gods are explainable magical phenomena that can be studied and controlled.
Having “atheist barbarians” dominate Peloria and locked in conflict with the dragon-mystic Orlanthi of the Empire of the Wyrms Friends gives us something that feels very different from our Third Age conflicts.
The atheist barbarians though were definitely preferably (at least to the Dara Happens and Rinliddi rebels) to the “Urox barbarians” of the later Carmanian Empire. This was founded in 1139 by usurpers from Vangstal and ruled until the Battle of Four Arrows of Light in 1147.
Of course, the Carmanian rulers are “barbarians” as far as the Dara Happens, Pelandans, and Theyalans are concerned. They speak a strange language, have odd customs, and their food is strange! And their bread is made of black rye, not wheat or barley. They worship our gods strangely, do not offer sacrifices to their own gods, and have evil sorcerers among them who claim to command gods and spirits.