The Breakdown
Era beginning/end
4543B.K.
The Breakdown was the event which separated Johorne from the rest of humanity.
Due to a cataclysmic event concerning The World of Souls, Johorne is broken away from its connection to the rest of Humanity. It is shrouded by the event and hidden from rediscovery for millennia. Due to this separation from humanity, the population on Johorne is struck by a sort of "spiritual amnesia," which resets their collective knowledge.