The First Jedi Schism was a conflict between the Jedi Order and the Legions of Lettow a few centuries after the formation of the Galactic Republic. The schism began after Xendor, a Dark Jedi Master who had been expelled from the Jedi Order years earlier, founded the Legions of Lettow and led them to Coruscant, the capital of the Republic, where Xendor attempted to destroy the Jedi Order. The Legions were defeated and Xendor was killed.
There was no record as to what happened to the surviving Legion members after the conflict, but a legend from Utapau stated that a relic called the Kaiburr crystal, which had been discovered by Xendor in the Unknown Regions, was taken to Utapau and hidden. The writings and teachings of Xendor were also taken to Conscio, a planet in the Outer Rim Territories, where they were discovered thousands of years later by the Ospion Guardians. The Ospion adopted the writings as the basis for their beliefs and became the Dark Jedi of the Bogan.
- Star Wars: Episode I - The Chosen One (First mentioned)