At the very start of the Great Crusade in ca. 800.M30, the planets closest to Terra could be easily reached by blind jumps through the Immaterium. The Empyrean of that time had only recently calmed after the great turbulence of the Age of Strife following the birth of the Chaos God Slaanesh. However, it soon became clear that to travel further from Terra, the Imperium's Navigators would require a stable astronavigational reference point within the Immaterium to triangulate their current location against if longer Warp jumps were to be attempted with any hope of success.