Afterlife

Afterlife is an abnormal star system created by the ancient Celestials as a place where powerful Force users could return to the land of the living. It was used by Sith for a period of time, but lost and forgotten until rediscovered by Emperor Palpatine. The passage of time is altered on Afterlife; time moves by more quickly in the rest of the galaxy. It also sits in the bottom of a deep gravity well; hyperdrives cannot leave the system. Only powerful Force users can leave the system.

Afterlife is a small, tidally locked planet orbiting a red star. The sunward half holds a citadel that was created for living beings to become hosts to Force spirits. Originally, individuals were bred and trained to become the perfect hosts to powerful Sith spirits, although inhabiting another being's body caused a lot of unwanted side effects. In more recent times, clones of the original Force-user are prepared and sent to the planet, resulting in a much more natural fit and making this "Force Resurrection" accessible to lesser Dark Jedi.

On the dark side of the planet resides the hosts deemed to insane or damaged to inhabit, as well as a variety of terrifying Sith abominations and strange creatures. That side is in perpetual darkness, lit only by the glow of ongoing volcanic activity. Deep in the heart of the dark side of Afterlife is the Tomb of the Old Sith. It held ten weapons, used in 2300 BBY to slay the ten Sith who had immortalized themselves on Afterlife and bind their spirits to the weapons that killed them. The lone surviving Jedi of that battle, Sarramis, remained on Afterlife to guard the tomb from Dark Side forces seeking to destroy the weapons and release the ancient Sith.

After the Jedi defeated the Sith in 2300 BBY, the planet was forgotten and remained lost until Emperor Palpatine discovered its secrets. He used some of the knowledge to transfer his being into clone bodies, eventually becoming powerful enough to do so without needing to visit Afterlife itself. It was one of his most closely guarded secrets, and knowledge of the planet died with him.

However, since the end of the Yuuzhan Vong War, somebody else has discovered the planet, and has been using it to create a new Sith Empire. The persons responsible for this are so far unknown.