Chisas was a secret planet the belonged to the ancient Sith Empire. On Chisas, Sith technicians managed to develop droids that could use the Force. However, before the droids could be sent into battle against the Jedi and the Old Republic, Exar Kun was defeated at Yavin 4. With the Sith Empire shattered, Chisas was quickly lost and forgotten, surviving only as myth and legend.
It wouldn't be discovered again until a few years after the Battle of Endor by a Defel Dark Jedi known as Sivter. His plan was to use Chisas to create an upgraded army of Force droids to bring a jihad against the galaxy. Sivter’s plans were thwarted however, by a small contingent of Jedi whose principle members included: Devon Vos, Jonji Fawkes, Tulsar Leidias, and Kalja Sairu Leidias.
Despite the Jedi’s best efforts, Sivter defeated one after another until Kalja exorcised the power of a Dark Lord of the Sith, known as Dragon Masque, from the Defel. Weakened, Sivter fled and activated the self-destruct for the droid factories to cover his escape and hopefully destroy the Jedi in the process.
The Jedi made it out alive, but the secrets of the Force droids were lost and buried. To keep anyone else from trying to resurrect such dangerous technology, the Jedi destroyed any trace of Chisas’s location and the planet has returned to being lost.
Years later Sivter would return to Chisas as the head of the Cult of Shadow. Since the location of Chisas was known to only a very few people, and since there was little reason for anyone to return to it with the droid factories gone, it made an ideal location for a prison facility. The facility, which wasn’t given a name, was used to house prisoners of the Cult of Shadow. Only a handful of people within the cult were trusted with knowledge about the facility, and even less knew that the true purpose of the facility was far more grand than housing prisoners…