Settled in secret around M30 or M31 in what is now know at the Handar Expanse, Pyr colony was founded as a haven for psykers, safe from the Black Ships and persecution by the Imperium of Man.
Amazingly, they do not seem to have faced Chaos incursions or other catastrophes despite sustaining a large population of unfettered Psykers. This might be because of the expanses’ relatively unspoiled status: It has not been touched by the forces of Chaos or of the Imperium.
The colonists have settled a close cluster of worlds deep inside the expanse, but have left other habitable systems untouched. They are ruled by a council of High Lords, who are all powerful psykers.