Sanctuary was a celestial body situated within the Slice region of the Outer Rim Territories. By the time of 2 BBY, this location served as a safe world for a covert organized rebellion against the Galactic Empire, discreetly guided by Senator Mon Mothma. This designation was recorded on a map of the galaxy, which identified various rebel havens, starfighter bases at level five or greater, rebel command centers, and shadow planets holding hidden space supplies. Initially dispatched to Mothma in 2 BBY, this map ultimately ended up with archivist Hendri Underholt, who included it in their collection of physical documents titled The Rebel Files.
The astronomical object known as Sanctuary was brought into the current Star Wars canon through the 2017 reference book Star Wars: The Rebel Files, penned by Daniel Wallace. The planet Sanctuary, which originated within Star Wars Legends continuity, was initially referenced in the first edition of West End Games' The Rebel Alliance Sourcebook, authored by Paul Murphy and published in 1990 for utilization with Star Wars: The Roleplaying Game.