The new official Clone Wars timeline has not yet been established by Lucasfilm. The exact chronology of the events described in this article is currently unknown.
Ilum was an ice planet in the Unknown Regions, one of the main sources of the valuable Adegan crystals used in the construction of Jedilightsabers. The caverns containing the crystals were long ago turned into a Jedi temple. Unlike the crystals of other planets, the crystals of Ilum were green, blue, red, yellow, and violet in color.
Ilum was first discovered in 22,800 BBY when a Jedi, navigating hyperspace in the Force, felt a strong pull from deep in the Unknown Regions. Following the sensation, the scout had found a world rich in Force-strong crystals—kathracite, mephite, and pontite. The mystique of the discovery added it to the ceremony of lightsaber construction.[3]
With a Temple established over the entrance to a series of Crystal Caves, Ilum became a place of great importance, as sacred as Ossus and Tython.[source?] The Temple served as a shelter and place of ritual for the Jedi who traveled to the planet.[7] To ensure the security of the planet and the crystals, the planet was left off star-charts. One uninterrupted hyperjump from Metellos would deliver a ship into Ilum's orbit, and could only be accomplished by a Force-sensitive.[3]
Following Ilum's discovery, the Jedi built temples and enclaves over the years and the world became a destination of pilgrimage for Jedi intending to construct new lightsabers and Jedi Masters seeking a quiet place for intense meditation.[1] Some time before the Cold War,[9] the Sith Empireattacked the planet with a force of Sith and shock troopers, killing the Jedi present there. Although the Jedi Order was devastated by the loss of Ilum, the Galactic Republic lacked the resources for a counter-attack. Intelligence suggested that the Sith operations on the world could have extended beyond the harvest of lightsaber crystals and, due to the amount of local Sith investments, Republic leaders and members of the Jedi High Council suspected that Ilum may have possessed a far more valuable resource.[1][10]
Obi-Wan Kenobi went to Ilum when he was young with his Master, Qui-Gon Jinn, to build one of his first lightsabers. As part of his training, Anakin Skywalker, along with his mentor and friend Kenobi, traveled to Ilum so that Anakin could build his first lightsaber. The two faced multiple challenges in scaling the slopes that lead up to the cave, including running into a nest of Gorgodons. Upon entering the cave, Anakin first faced Darth Maul's ghost before finally completing his lightsaber.
Around 20 BBY,[13] Yoda and Padawan Ahsoka Tano led a group of promising Jedi Initiates in the ritual known as The Gathering, where they would brave the dangers of the Crystal Cave and find crystals to make their own lightsabers.[7]
Because its existence was not known generally to non-Jedi, Ilum was virtually forgotten after the destruction of the Jedi and Palpatine's information purges. This gave the remaining Jedi a safe harbor. After Order 66, Obi-Wan Kenobi received intelligence that his friend, Jedi MasterGaren Muln, had returned to Ilum to hide in the crystal caves. Ferus Olin, a former Jedi apprentice, returned to the caves to retrieve crystals to build a new lightsaber. He also found Garen. The Jedi Master had grown weak during his time on Ilum. He gave Ferus his old lightsaber, which needed new crystals. Ferus inserted his crystals and carried the weak Jedi Master out of the caves. Obi-Wan came to their rescue before the Imperials could take them hostage.
Another Jedi also took refuge there: Fy-Tor-Ana. However, according to Garen, she returned to Coruscant to see if any other Jedi had survived. She did not return, but it was rumored that she was imprisoned on Coruscant.
This section of the article assumes 100% game completion of Star Wars: Empire at War. Alternate stories are noted in the "Behind the scenes" section. Note: The events in this section may or may not be canon.
During the Empire's hunt for MoffKalast, who was leaking information to the Rebels, they discovered a Black Sun base above Ilum. Boba Fett, in the Slave I, disabled their sensors so an Imperial fleet could capture the pirate leader.[8]
In the Star Wars: Clone Wars TV series, purple crystals are seen to fall, even though it is stated to only produce blue and green crystals.
Ilum is also a planet for end-game content in Star Wars: The Old Republic where players can complete both PvE and PvP daily missions. Two of the game's final instances are also located there.