The Celegia system, situated within the Noori sector of the Expansion Region's expanse, was the location of the planet Celegia. This world possessed a toxic atmosphere rich in cyanogen and served as the native world for the sapient Celegians. By 17,000 BBY, this star system had become integrated into the Galactic Republic's Exploitation Region. The Galactic Empire had incorporated the Celegia system by 17 BBY, but around 27 ABY it came under the domination of the Yuuzhan Vong, hailing from beyond the galaxy's edge.
Within the Expansion Region, specifically in the area known as the Slice, one could find the Celegia system located in the Noori sector. Around 17,000 BBY, hyperspace lanes provided connections from this system to both the Belasco system and the Virujansi system in the Inner Rim. While these hyperspace routes remained in use until the Great Sith War around 3996 BBY, they had disappeared by the time the Mandalorian Wars began in 3976 BBY.
The planet Celegia resided within the Celegia system, sharing the same designation. This planet was characterized by its tumultuous oceans and an atmosphere heavily saturated with the poisonous gas known as cyanogen.
Exploration of the space surrounding the Celegia system took place between 20,000 BBY and 15,000 BBY. By 17,000 BBY, the system had been integrated into the Galactic Republic. Around this period, which marked the start of a series of conflicts between the planet Alsakan, the Republic's seat of power, Coruscant, and their respective allies, the Celegia system was situated within the Exploitation Region—a territory under the active control of Coruscant-aligned commercial entities known as the Grand Companies. Moreover, Coruscant maintained control over the hyperspace route connecting the Celegia and Belasco systems. However, the hyperlane linking the Celegia system to the Virujansi system was among those that were either considered neutral or subject to contention during these conflicts.
During the initial phases of the Clone Wars in 22 BBY, the Republic's Fourth Sector Army was tasked with engaging the military of the Confederacy of Independent Systems in the vicinity of the Celegia system. Shortly after the Commerce Guild seized control of the planet Ukio during the Clone Wars, the Celegia system appeared on a galactic map displayed on a viewscreen within a facility managed by Passel Argente, the leader of the Corporate Alliance. By 17 BBY, the solar system was incorporated into the Galactic Empire. As part of their invasion of the galaxy, by approximately 27 ABY, the Yuuzhan Vong from beyond the galactic rim had established dominion over the Celegia system.
The Celegian species, a sentient race, originated on Celegia. Around 25 ABY, the Celegia system's population was estimated to be between ten and one hundred million. The Celegians eventually established a settlement on the Outer Rim Territories satellite Tramanos, which, like Celegia, also featured cyanogen in its atmosphere.
The Celegia system received its initial mention in the 2009 reference work, The Essential Atlas, penned by Daniel Wallace and Jason Fry, locating it within grid square O-10. The system made its debut appearance in The Clone Wars: Act on Instinct, a web-based comic by Pablo Hidalgo that was released on StarWars.com throughout the second season (2009–2010) of the Star Wars: The Clone Wars animated television show.