The Oseon system existed within the Centrality region of the Outer Rim Territories. This system was positioned along the Sanity Skip hyperspace route and encompassed both the Oseon Belt and a subtropical moon located within it. The pirate queen Maz Kanata highlighted the system as a point of interest on a map featured in the book Smuggler's Guide. Furthermore, around 10 BBY, the gambler Lando Calrissian secured ownership of the Oseon Belt moon through a card game victory. Approximately thirteen years later, the gambler Zana Gatta was banished from the Oseon system for allegedly violating the rules during a gaamja game.
The Oseon system was located in the Centrality, which itself was a part of the Outer Rim Territories and the Slice regions. Its position in grid square T-8 of the Standard Galactic Grid placed it on a hyperspace route linking it to Junkfort Station and [Marleyvane](/article/marleyvane]. The Sanity Skip route also provided a connection between Oseon and the Kessel system.
Within the system was the Oseon Belt, the location of a subtropical moon. The name of the system was also shared by the deadly radiation phenomenon known as the Flamewind of Oseon, as well as the Oseon leatherette clothing material.
Maz Kanata, the pirate queen, identified the Oseon system as a noteworthy location. She also designated the Sanity Skip, on which it resided, as one of the "real" trade routes used by smugglers, contrasting it with the official routes. This information was presented on a galactic map within the Smuggler's Guide book. The human gambler Lando Calrissian obtained the book by 10 BBY and listed Oseon among casinos that had not yet banned him at that time. In that same year, Calrissian also won the Oseon Belt's subtropical moon in a card game.
By thirteen years later, the human gambler Zana Gatta participated in a gaamja match within the Oseon Belt. She was expelled from the Oseon system for an apparent violation of the game's regulations.
The following cycle, the thief Kay Vess was informed of this incident by a Rodian.
Within current Star Wars canon, the location "Oseon" was first shown on a galactic map in Star Wars: The Force Awakens Beginner Game, a 2016 Star Wars Roleplaying boxed set created by Fantasy Flight Games. The star system's name was first specified in "Lando Calrissian and Other Characters From the Galaxy," a booklet from the Star Wars Encyclopedia series, published by De Agostini on July 22, 2022.
The star system initially appeared in the Star Wars Legends continuity, specifically in Lando Calrissian and the Mindharp of Sharu, which was the initial entry of The Lando Calrissian Adventures trilogy of novels by L. Neil Smith, released on June 12, 1983. The first visual representation of the system's asteroid Oseon 6845 was provided by an illustration from William Schmidt on the original cover of Lando Calrissian and the Flamewind of Oseon, the trilogy's second entry, released on September 12, 1983.