Star Wars has finally revealed what happened to a Sith cult active in the sequel era. Chuck Wendig's Aftermathtrilogy was envisioned as an essential setup for the sequels, three novels set in the immediate aftermath of Return of the Jedi that revealed how the galaxy changed after the (apparent) death of Emperor Palpatine. The story culminated in the Battle of Jakku, the final defeat of the Emperor, and the end of the Galactic Civil War.
The books introduced a Sith cult known as the Acolytes of the Beyond. Formed by Palpatine loyalist Yupe Tashu, the members of the cult were not Force-sensitive themselves but they were obsessed with collecting Sith artifacts. They tended to wear ancient Sith masks, steeped in the dark side of the Force. Most readers assumed they were supposed to foreshadow Kylo Ren and his Knights of Ren. These theories are probably accurate, but Lucasfilm's plans weren't especially thorough, and the sequels pivoted in a different direction. The Acolytes of the Beyond became an irritating loose plot thread.
Related: Star Wars Finally Explains The Rise Of Skywalker's Sith Dagger
Adam Christopher's Shadow of the Sith finally explains what happened to the Acolytes of the Beyond. It seems that Luke Skywalker and his ally Lor San Tekka heard rumors they were amassing their own arsenal of Sith artifacts in an attempt to harness their dark power. Luke and Lor found the Acolytes to be a splintered, disorganized cabal, fascinated by the dark side but unable to truly wield its power. Luke shut the Acolytes of the Beyond down, taking their treasure trove of artifacts into his own keeping, and even redeemed one of their number.
Luke had underestimated the Acolytes of the Beyond, however, because one of their members
Read more on screenrant.com