The Endor Sith were a faction that broke away from the Night Jedi, precipitating a war on the moon.
A Sith Marauder, Incursionus, landed on the moon, and soon engaged in combat with the Night Jedi Jobie Wan Kenobi. With the assistance of Diaeta, Incursionus was captured, and kept within the Night Jedi Citadel's holding cells.
However, Diaeta fell to the ways of the dark side, and broke Incursionus out of the Citadel, retreating into the deep forest where they began to construct a new Sith Citadel.
Soon, the Night Jedi discovered the Citadel and decided that this Sith threat could not be allowed to continue, and as such they initiated an attack against the group of Sith. Tanek, a highly respected member of the Night Jedi Order, faked a defection to the Sith, infiltrating their facility.
As Night Jedi forces surrounded the Sith Citadel, many of the Night Jedi leadership dueled with the Sith, leading to the recapture of Diaeta. Incursionus escaped with Tanek, still under the guise of the Sith, back inside the Citadel, where Jobie Wan and Pryce Fisto tracked them down. A final duel was fought, resulting in the end of the Endor Sith.
Behind the Scenes
Due to the move to Universe 1.5, not all characters still roleplay. This has resulted in the result of the final duel being invented without roleplaying, to allow the remaining characters to continue playing.