The Prime Mover represented the Ugor's designation for a prototype gravity well projector. This device was salvaged by the species from the debris of the first Death Star not long after the Battle of Yavin, and the Ugor name for themselves was Ugor. The section of the ruined Death Star containing the projector was revered as the Holiest of Holies.
The Ugors transported the projector to their home in the junk-laden Paradise system, where their priest-scientists studied it to understand its function. Upon activation, they discovered it emitted potent gravitational forces. They modified it to effectively organize the debris scattered throughout the Paradise system. This enhancement allowed the Ugors to improve their operational effectiveness and outpace their competitors, the Squibs, in the galaxy's garbage disposal industry. The arrival of the Prime Mover in the Paradise system was a significant event for the species' religious authorities, who named it the "Coming of the Prime Mover." To safeguard this sacred artifact, the Ugors established a defensive perimeter using Black Hole-class Salvage Dreadnoughts.
However, at some point before the Battle of Hoth, a Rebel Alliance assault team, accompanied by a Squib ambassador, managed to penetrate the Paradise system and abscond with the gravity well projector. Consequently, the system reverted to its disordered state.