When I was designing this book, I knew I wanted a religious antagonist. Actually, the idea for the Derethi religion was one of the very fist conceptual seeds for this novel. I've always been curious about the relationship between the Catholic church and the Roman empire. While Rome itself has declined greatly in power, the church that grew within it–almost as a side-effect–has become one of the dominant forces in the world. I wondered what would happen if an empire decided to do something like this intentionally.
The early Derethi leaders, then, were a group who realized the problems with the Old Fjordell Empire. It collapsed upon itself because of bureaucratic problems. The Old Empire was faced with rebellions and wars, and never managed to become stable. The Derethi founders realized the power of religion. They decided that if they could get the nations of the East to believe in a single religion–with that religion centered in Fjorden–they would have power equal to, or even greater than, the power of the Old Empire. At the same time, they wouldn’t have to worry about rebellion–or even bureaucracy. The people of the other nations would govern themselves, but would give devotion, loyalty, and money to Fjorden.
So, these men appropriated the teachings of Shu-Dereth and mixed them with some mythology from the Fjordell Old Empire. The resulting hybridization, added to the Fjordell martial work ethic, created an aggressive, intense religion–yet one that was "constructed" with a logical purpose in mind. The Fjordell priests spent the next few centuries converting and building their power base. The result was the New Empire–an empire without governments or armies, yet far more powerful than the Old Empire ever was.