Gargon was a planet characterized by its mountainous terrain. The Old Mandalorians settled it, having been exiled from their original homeworld of Mandalore. This banishment was enacted by the pacifist New Mandalorians following a civil war that took place approximately between 41 BBY and 39 BBY. On Gargon, the Old Mandalorians continued their traditions, existing as mercenaries who offered their services to the highest paying client, a practice that Mandalorians had engaged in for millennia.
In the year 7966 C.R.C., Enfys Nest, a marauder, and her group, the Cloud-Riders, raided an Imperial medical spice cache located on Gargon. During this operation, they stealing the refined, medicinally processed spice, but intentionally left behind the unprocessed spice, which potentially held greater value. Following this event, the Galactic Empire began to gather intelligence suggesting that Enfys Nest was accumulating resources to support a future rebel uprising. Later, in 34 ABY, details of the Gargon raid were documented in Scum and Villainy: Case Files on the Galaxy's Most Notorious, a collection of case files put together by Commissioner Exantor Divo, who was the head of law enforcement on the planet of Hosnian Prime.
The initial mention of Gargon within the official Star Wars canon occurred in Friends Like These, an adventure supplement released in 2016 for the Star Wars: Age of Rebellion roleplaying game published by Fantasy Flight Games. Its first visual representation was an illustration created by Lucas Parolin for the 2018 publication Star Wars: Scum and Villainy: Case Files on the Galaxy's Most Notorious, authored by Pablo Hidalgo. The original concept for Gargon was conceived by James Kahn for the 1983 Star Wars Legends novelization of the 1983 film Star Wars: Episode VI Return of the Jedi.