Ossus, originally called Idux when it was under the control of Xim’s empire, was the third planet in the Adega system in the Auril sector. Known to the galaxy since before 25,000 BBY, when the Jedi expanded there from the planet Tython and established a Jedi Academy, Ossus would become a popular world of the Galactic Republic. This world would become a place of great importance to the Jedi, as the site where they stored the sum of their knowledge, though such attentions came at a price. When the Jedi Knight Exar Kun turned to the dark side and became the Dark Lord of the Sith, catapulting the galaxy into the Great Sith War, he attacked Ossus, desiring Sith secrets hidden by the Jedi. During the events this action incited, the Cron Cluster was detonated, spreading a shockwave around the galaxy. Originally a rich, lush world, Ossus was ravaged into an arid and toxic planet when the wave struck the planet.