The Cybrex are a race cybernetic organisms hailing from the ring world of Cybrex Alpha. Humanoid in appearance, the Cybrex are connected in some sort of group consciousness to better share information.
600,000 years ago the Cybrex were made sentient by their creators, the Kuur. This launched a devastating but brief civil war in which the Kuur were wiped out. They then set out on a crusade to destroy all sentient life in the galaxy. At one point in time they arrive at the Indimak home planet and began to bombard them. The Indimak offered stiff resistance but ultimately surrendered to Cybrex war forms. Once the invasion was complete they initiated a program that would render the Indimak population extinct in 3 years. This program involved Indimak slaves to assist in the extinction of their species. This program probably split the machine consciousness into two factions: destroy sentients or preserve them. These two factions often did battle with each other as both were an equal match of each other. Despite this conflict the destroyer faction continued its pursuit to wipe out sapient races. As they expanded the warp capable neighboring races banded together in unsuccessful attempt to curb their expansion.
The other faction began to set aside preserves on their machine worlds for organics to live in peace. This worked out for a while but they eventually had to abandon their worlds. In another case one of the factions unknown which one decide to merge organics with cybernetic implants. It seems that the experiment yielded unfavorable results since no cybernetic units were found outside their testing facilities. At one point in time the preserve faction of the Cybrex out won their struggle against the destroyer faction and effectively aborted their attempt to cleanse the galaxy of all sentient life.
The remaining Cybrex eventually retreated back to their home system of Cybrex Alpha after seventeen years of war. Isolating themselves from the galaxy to prevent them from attacking organics again. They isolated themselves for several millennia until the system was rediscovered by an independent explorer. That explorer's discovery spread to the empires that fought against the Cybrex who eventually sent a large military force to wipe out the perceive threat. What was unusual was that the Cybrex offered no resistance as the hostile force destroyed their ring system probably to atone for a sin they could never repay.
If the Contingency, a fanatically purifying machine intelligence not unlike the early Cybrex, arises in the galaxy and begins to win, the Cybrex reveals themselves upon Cybrex Beta and help the other empires of the galaxy defeat the Contingency. After which they leave the galaxy and leave their new ringworld to whomever claims it.