The Chrelythiumn system, a star system, existed in the uncharted territories of Wild Space, significantly past the boundaries of the Outer Rim Territories. During the period of conflict known as the Clone Wars, the Mortis monolith materialized within the system's depths, emitting an age-old distress signal associated with the Jedi. Consequently, the Jedi High Council dispatched a team comprised of Jedi Master Obi-Wan Kenobi, Jedi Knight Anakin Skywalker, and his Padawan, Ahsoka Tano, to investigate. They were instructed to meet up with a heavily-armed Jedi cruiser in order to defend against a possible deception by the Separatist forces.
This star system, known as the Chrelythiumn system, was located at galactic coordinates K-2 on the Standard Galactic Grid, within the area of Wild Space beyond the Outer Rim Territories. A massive, dark red crystalline structure, the Mortis monolith, was present in the system, acting as a gateway to the ethereal realm of Mortis.
Sometime during the Clone Wars, a conflict between the Galactic Republic and the Confederacy of Independent Systems, the Mortis monolith mysteriously appeared deep within the Chrelythiumn system. Following this event, the Jedi Order, based on the planet Coruscant, received a very old distress signal, one that had not been used for over two millennia (years). As a result of receiving this signal, the Jedi High Council dispatched Jedi Master Obi-Wan Kenobi, Jedi Knight Anakin Skywalker, and his Padawan, Ahsoka Tano, to the Chrelythiumn system in order to investigate the signal's origin. To support the Jedi in case of a Separatist trap, the Republic also sent a heavily armed Venator-class Star Destroyer.
When the starships arrived, neither the Jedi nor the personnel of the Star Destroyer, which included Clone Captain Rex, could detect each other on their scanners, causing confusion among both groups. Suddenly, the Jedi shuttle's communications were severed, and the Mortis monolith manifested before them, pulling them into the enigmatic Force realm of Mortis. After an adventure that resulted in the deaths of the three god-like Force wielders residing on Mortis, Skywalker, Kenobi, and Tano found themselves back on their shuttle within the system. Re-establishing contact with Rex, they discovered that, from the perspective of the outside universe, their shuttle had only been gone for a brief time. After explaining to a puzzled Rex that their experience had lasted much longer, Skywalker piloted the shuttle to the Star Destroyer.
The Chrelythiumn system made its initial appearance in the Star Wars: The Clone Wars season three episode entitled "Overlords."