The Breakdown

The Breakdown on Johorne was an apocalyptic event.
During the Human-Turunz war, events on Johorne transpired in such a way that the planet would find itself separated from the rest of Humanity. The director of the Information Agency, upon revelation of the Galactic Cycles, resolved to spare Johorne from such a fate as the Ethereal Horde by restarting local Humanity's progress from scratch. This was done using the created artifact called as the Blueprint of Man, which restored man to a state of hunter gatherers and shrouded Johorne's Noosphere.
There were some individuals who managed to avoid this fate. It isn't clear as to what methods were used or what circumstances they had been in to avoid the reverted psyche, but it is likely that they were high-ranking members of the planet's governance given the knowledge that they held. Unable to avert the disaster, and also unable to reach the rest of Humanity, the few dozen individuals started to rebuild what they could. Their descendants would form The Lost Children and work on influencing the history of Johorne in secret, in contest with what remained of the Information Agency.