Located deep within the Nameless Nebulae, Y was formed at least 8 billion years after the big bang, presumably much earlier than even that. (Out of the White Hole) Planet Y, at the time of its colonisation, was a world covered by boundless oceans, with underground caverns and fields of crystal.
Y was colonised by members of planet Alpha. The Alphans departed from their home world to escape extinction by the hand of the Frame (Star of Sirrah), and chemically modified themselves to survive in the ocean-covered world. The adapted Alphans call themselves Forever. Forever essentially became one with the ocean world, since the radiation from Sirrah's Eye prevents them from leaving the planet.
After their escape from Alpha and The Frame, Forever originally vowed to never let machines control their lives again. An android that accompanied them from planet Alpha, TH1, in quest for new purpose, decided to evolve and grow, and become the new Frame. It is unclear where the materials required to do this would have come from, but it is possible parts of the Starblade were re-purposed. Despite their original intents, Forever failed to stop technology from taking over their lives again.
After years of technological development, the race, Forever, covered the entire planet in giant machines designed to improve their quality of living, eventually granting them biological immortality, probably due to a never-ending supply of Liquid Eternity. Unable to withhold their compulsion to expand their nation and territory, Forever rose from the depth of the aquatic world, and it is implied that they now live in mechanical compartments near or on the surface of the planet. They became so dependent on their mechanical components that they lost their emotions and built infrastructure so tall that it blocked out the light from their own sun in a time known as the Age of Shadows (Age of Shadows, Liquid Eternity). Forever live isolated from each other, in capsules that keep them alive, while communicating with each other using telepathy.
Forever reminisces of the times when before technology took over, and they were free to roam their world as desired. (Beneath the Waves)