A Sith demon was a formerly dead being who had been revived through the Force before they could become one with it. Sith demons were compelled to serve the will of the Sith who raised them. During the Sith rebellion led by the Dark Lord of the Sith later known as the Ronin, the witch who accompanied him would revive dead Sith warriors, forming a demon army that battled alongside the living Sith in their war with the Jedi. During a final great muster on Rei'izu, the female Sith and later bandit leader Kouru witnessed the witch raise demons, and observed they were little more than shades that did not last long and had no will of their own. Some of the tales spread about the rebellion referred to the practice as unholy sorcery and blasphemy against the natural order.
Twenty years after the collapse of the rebellion, the Jedi clans and Jedi lords had grown in power. Mirahi, the daughter of the Ronin and the witch, continued her mother's practice. After Mirahi inadvertently killed her mentor, she resurrected them and they became the Traveler. She turned many dead Jedi into Sith demons, preventing the Jedi clans from recovering the bones of dead Jedi and leaving battlefields empty of bodies.
In a skirmish on Genbara, the Ronin dueled with Kouru and killed her within a temple. Mirahi resurrected Kouru as a Sith demon to use against her father; however, Kouru proved more capable of independent thought than most demons.