The Devisors were the descendants of the starship engineers of the colony ship Exocros Cabal, who had first settled the planet to escape pirates and stop the infighting that plagued the families on the ship. After settling on Exocron, they deliberately destroyed the hyperdrives of the Exocros Cabal to keep the fledgling colony intact in the early years.
Over the years, the group evolved into a secretive sect who viewed all technological advancement as evil, and they forbade space travel of any kind. They believed it would destroy the civilization, and claimed that any outside contact would destroy Exocron since they did not have the technology to safeguard the planet. In reality, the Devisors had access to advanced technology, including the secrets of spaceflight, and control of at least one powerful tractor beam capable of snaring ships in orbit.
The Devisors ruled over the planet Exocron with an iron fist, but there was resistance to their rule from those who believed the Devisors were denying them their birthright. Any technological development was given to the masses only after the Devisors had ensured that it posed no threat to their rule. Only those trusted with the secrets of high technology, such as the chief engineer and apprentices on board Airfleet vessels were allowed to maintain and repair the mechanical and technological systems.
The Devisors understood that knowledge is power, and as time passed, became more aware that the galaxy at large had moved on technologically, and that they were being left behind. As this realization grew, so did their isolationist stance. When the New Republic ship FarStar discovered the planet in 8 ABY, the Devisors saw that the ship and her crew represented a source of technology and knowledge far greater than their own, and was thus a threat to their rule. They ordered that the ship would be studied in the hopes of finding a way to protect the planet from future threats. In reality, they were hopeful that study of the FarStar would increase their tenfold.
Unfortunately for the Devisors, the decision to hold the FarStar and her crew set off a chain of events that led to the resistance in Caballa City taking control of the Ministry of Technology and destroying their powerful tractor beam. The Devisors were deposed, and the Ruling Council took control of the planet.