Drujan is the equilavent of Azerbaijan in the Kushielverse. The capital is Darsanga. During the events of Kushiel's Avatar, Drujan is ruled by the insane and blood thristy Mahrkagir (conqueror of death) and his priests called Aka Magi (elsewhere refered to a Skotophagoti or bone priests). They are thought to have the powers to kill by merely touching their shadow.
At some point prior to Kushiel's Avatar, Drujan was ruled by Khebbel-im-Akkad. At that time, the Drujani people practiced a religion based on Zoroastrianism, worshipping Ahura Mazda. However, when the Mahrkagir and his Aka Magi took control, they perverted their faith and worshipped Angra Mainyu, the destructive spirit.
Khebbel-im-Akkad sent their army to Drujan to try to regain their hold on the land. Their army was defeated, and the soldiers that lived reported having turned on each other. In Khebbel-im-Akkad, it is illegal to trade with the Drujani or the Aka Magi.