Towards the end of the Age of Technology psykers first appeared among humanity. While persecuted on many backwards, regressive human worlds as witches, in enlightened and progressive societies these psykers were at first protected and accepted. The initial intolerance for psykers would later seem prescient, as many human worlds fell to the dominance of daemons and other Warp creatures using possessed psykers as gateways into the physical world. Only worlds which had rigorously suppressed psykers survived the Age of Strife.

Even worse, following the destruction caused by the war against the Iron Men, human psykers began to appear in large numbers across many human colony worlds, one of the harbingers of the final decline of the Eldar empire which controlled even more of the galaxy than mankind did in these years. The result was humanity's first introduction to the daemonic horrors of the Warp and the ultimate collapse of human interstellar civilization during what became known as the Age of Strife.