Ossus

Ossus, known as Idux while 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 Order expanded there from the planet Tython and established a Jedi Academy, Ossus would become a popular world of the Galactic Republic. This world would also 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.

Certain individuals survived the blast, including several Jedi. Over the passing generations, these people would become more feral, forgetting their heritage and the Force while regarding their abilities from it as magical. They became the Ysanna, Ossus's only native sentience. They, along with the planet, lived in peace with the rest of the galaxy through the Clone Wars between the Republic and Confederacy of Independent Systems, when Ossus primarily became a planet of archaeological importance to the Jedi. Once the Galactic Empire rose to replace the Republic, such studies into the past of the Jedi were halted, however.

After the eventual fall of that government as well, and the rise of the New Republic, Ossus saw major use during a time of war, for the first time since the Sith War of 3996 BBY, during the Yuuzhan Vong War of 25 ABY. It was studied by the Yuuzhan Vong, extra-galactic invaders who wished to conquer the galaxy, while they searched for a way to gain the upper hand against their primary enemies, the Jedi and New Republic, who in turn used it as a rally point for assaults against the Yuuzhan Vong. Ossus regained its standing with the Jedi, revived as the New Jedi Order, following the war. Jedi Grand Master Luke Skywalker reopened the Academy there and made it the headquarters of their organization, though he later returned that distinction to the Jedi Temple on the galactic capital of Coruscant.

In an attempt to allow the Yuuzhan Vong to redeem themselves a century later, Skywalker's descendant, Kol Skywalker, founded the Ossus Project, an initiative to use Yuuzhan Vong terraforming to restore the surface of Ossus. Due to Sith sabotage, the project failed and infected many individuals with organic parasites. The devastating effects the parasites had on people prompted the Fel Empire to call for an end to the project, which the Jedi would not allow. When the Galactic Alliance defended the Yuuzhan Vong at the request of the Jedi, the Empire declared war against their loose rival, crippling and defeating them in 130 ABY. The Jedi moved their headquarters to Ossus once again after Coruscant was ceded to the Empire and Sith. However, two days later, the Sith attacked the Ossus Academy, killing half the Jedi inside and beginning the galaxy's third Jedi Purge. The Empire would later level the entire Academy in a barrage of turbolaser fire.

Text and facts from the “Ossus/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.