The Dark Brotherhood was an order of knights in the Drenai world. They were also referred to as the Knights of Blood, the Dark Templars or the Dark Knights.
The Brotherhood worshipped the Chaos Spirit and used their Talent for nefarious purposes. They were the evil equivalent of the Thirty and their numbers were often greater than the warrior priests'. Unlike the Thirty, the Brotherhood were not true mystics, because they used the Lorassium leaf to "walk the mists" and release their spirit forms.
The Brotherhood was formed in and around the year 783 in Chiatze by Zhi Zhen. After Zhi Zhen was defeated and impaled, the Brotherhood spread west over the course of the next few hundred years where they were later used by General Kaem during the Vagrian Wars.