The Underground, also known as Jah Unubunko, is a Coruscant criminal society, which is believed to have emerged right after the battle of Yavin. It is a loose association of criminal groups, that share a common organisational structure, and code of conduct. Each group, known as a “Tribe” or “Kapa”, claims sovereignty over a territory in which it operates its rackets, usually a neighbourhood of a city. Offshoots of the underground emerged in Tatooine and in Corellia, right after the battle of Yavin following waves of Coruscanti immigration. The genesis of Jah Unubunko is hard to trace because of its secretive nature, and lack of historical record-keeping.

It is widely believed that its seeds were planted in the upheaval of the galaxy transition, during the battle of Yavin to right after the battle of Yavin, and its later annexation by the Galactic Government of that time. The Coruscant state could not fully enforce law and order. Many groups, from bandits to artisan guilds, used violence to plunder or settle disputes. The common traditions, and structure that distinguishes The Underground, may have been shared between criminals in prison. For that very reason, there is a saying that once your with the Unubunko, the only way out is death.