During the Great Crusade, the Manachea System was the source of an advanced Human civilization that numbered in the hundreds of millions. However, it was controlled by the Mitu Conglomerate, a cabal of psychic xenos. Warp-capable and with arcane technology, they forged a pocket empire, forbidding any attempt of space flight and purging all psykers. The tyrannical rulers demanded a periodic culling of their subjects' population and tributes of flesh to power their technologies. After a protracted and bloody war during the Great Crusade, the Mitu Conglomerate was annihilated by three Space Marine Legions and hundreds of Solar Auxilia cohorts.
After its conquest, the human population of Manachea, perhaps used to submission, welcomed their new Imperial rulers with open arms. The worlds of the system were thereafter organized into a semi-autonomous commonwealth that came to dominate the region of space. However, during the Horus Heresy, the Manachean Commonwealth was ravaged in the Battle of the Coronid Deeps.
- Manachea Lux — Industrial World. Arid and highly productive. It was the site of the last battle to liberate the system. It the Imperial Fists Fortress of Bastion Kvet, erected by Rogal Dorn on the promise that the world would never fall under xenos domination again.
- Manachea Vysidae — Hive World. Principle world of the system, often simply referred to as Manachea. It had a population ranging in the tens of billions and a production level rivaling the Hive Worlds of Segmentum Solar by the Horus Heresy.
- Manachea Mortis — Death World. Jungle-shrouded moon of the gas giant Manachea Umbris. Home to lethal fauna but still manages a native human population. It often acted as a world for refugees and outlaws.