Timeline of the Warhammer 40,000 Universe - Great Sleep: The Necrons had been vindicated in their pursuit only of science and control over the material realm and certainly took pleasure in seeing the Old Ones' civilisation collapse as a result of their over-indulgence of psychic power and the end of the C'tan's domination over their species. Yet even with the defeat of the Old Ones and the C'tan alike, the Silent King saw that the time of the Necrons in the galaxy was over -- for the moment, at least. They would allow the Enslavers to take what was left of the intelligent life in the galaxy and let it become an interstellar wasteland; the psyker swarm would then die away and in time the galaxy would evolve new lifeforms who would be less sophisticated and easier to dominate.In addition, the Necrons understood that the mantle of galactic dominion was soon to pass to the Aeldari, one of the psychically-potent species that had fought alongside the Old Ones throughout the War in Heaven and had thus come to hate the Necrons and all their works with the burning passion that is the defining characteristic of that species. The Aeldari had survived where the Old Ones had not and the Necrons, weakened by their expenditure of lives and resources in overthrowing the rule of the C'tan, could not stand against them.Yet the Silent King knew that the time of the Aeldari would eventually pass, as it must pass for all those beings still cloaked in flesh. It would take millions of Terran years for the Aeldari's power to fade, but what mattered is that the Necrons would be there to take advantage of it.So it was that the Silent King ordered the remaining Necron cities to be transformed into great tomb complexes threaded with stasis-crypts. Let the Aeldari shape the galaxy for a time -- they were but ephemeral, whilst the Necrons were undying and eternal. The Silent King's final command to his people was that they must sleep for the equivalent of 60 million standard years but awake ready to rebuild all that they had lost, to restore the Necron dynasties to their former glory.This was the Silent King's final order, and as the last Tomb World sealed its subterranean vaults, Szarekh destroyed the engrammatic command protocols by which he had controlled his people for so long, for he had failed them utterly. Without a backward glance, Szarekh, the last of the Silent Kings of the Triarch, took ship into the starless void of intergalactic space, there to find whatever measure of solace or penance he could.Meanwhile, aeons passed and the Necrons slept on, their machine slaves and constructs guarding them while they slept on Tomb Worlds that had been purged of all life to keep the Enslavers from their door. This plan worked with an amazing degree of success until the Necrons were awakened by the forces of the Imperium of Man in the 41st Millennium to plague the galaxy once more. They discovered a new and unexpected age of interstellar civilisation and war much like the one they had left behind 60 million standard years before.The galaxy is blossoming with life once more but is still overrun with latent psykers and worshippers of the infernal Chaos Warp energies first unleashed during the War in Heaven. It will take time and a great many machinations for the Necron dynasties to regain their rightful place as the rulers of the galaxy; the agents of Chaos must be overthrown; the dangerous Aeldari, inheritors of the Old Ones' mantle, eliminated; Humanity subjugated and the great work cutting off the material universe from the Warp completed before a new age of Necron dominion can truly begin.But the Necrons are ageless and undying, their technology still unmatched by any of the younger starfaring species. And time is always on their side...