Old Ones - War in Heaven: Before the creation of the Aeldari, the Old Ones were at war with the Necrontyr over 60 million Terran years ago, a conflict later remembered by the Aeldari as the "War in Heaven." One of the few already sentient species the Old Ones had encountered as they traveled across the galaxy were the humanoid Necrontyr, who at the time were in the midst of a slow, sublight interstellar expansion to distant planets beyond their home star system.The lives of the Necrontyr were always short and painful due to the deadly radiation of their world's sun and their evolutionary adaptations to it. When the Necrontyr met the Old Ones, they developed a deep, jealous hatred of the reptilian aliens due to their near-immortal lifespans. The Necrontyr are said to have petitioned the Old Ones for the technological secret of eternal life but they refused, engendering an even more terrible rage in them.This resentment led to the first interstellar war ever fought in the galaxy. Possessed of far inferior technology, the Necrontyr's war against the Old Ones to claim the secrets of life everlasting proved futile and they were forced back to their remote world in the outer rim of the galaxy's Halo Stars. The fury of the Necrontyr cooled over thousands of Terran years of imprisonment by the Old Ones, but they eventually turned their hatred against their jailers upon all other forms of life.The Necrontyr had studied their star for millions of Terran years. In their quest for a weapon to use against the Old Ones who had prevented their interstellar expansion, they found the intelligent race of energy beings known as the C'tan. Gradually the Necrontyr managed to communicate with these ethereal beings composed of pure energy who fed on the electromagnetic energy emitted by the stars, but the C'tan knew they would never be able to fully comprehend the material universe without a material body.So the Necrontyr built the living metal bodies from the alloy they called necrodermis that the C'tan are still adorned with. The C'tan were soon worshipped by the Necrontyr as their Star Gods, as their powers and intelligence were far beyond anything the Necrontyr had experienced before, even in their encounters with the Old Ones. As the C'tan became more manifest in their new physical bodies, they began to enjoy certain aspects of material life more, including the infliction of pain, suffering and slavery -- and discovered that the energies given off by corporeal life were far more savoury than the bland solar emissions that had always been the mainstay of their diet.The C'tan next provided the Necrontyr with an escape from the curse of their short lives. The C'tan offered to transfer the Necrontyr's minds into living metal bodies comprised of necrodermis, much like the C'tan themselves. The C'tan eventually tricked the Necrontyr into transferring their own consciousnesses into robotic bodies made out of the same necrodermis material. Once the Necrontyr had done so, they discovered to their horror that their new bodies erased their psychic impressions in the Warp, effectively rendering them as soulless as the C'tan themselves.Whether the Necrontyr knew what they would lose by undertaking this biotransference will never be known, but the process essentially destroyed their people. The Necrontyr gained the immortality they had so craved but lost their free will. Their minds were dulled and only a few members of the species, the Necron Lords and Overlords, retained any independent thought. Unfortunately, the side effect of the biotransference process was that the Necrontyr, now calling themselves "Necrons," gradually lost the ability to feel any emotions at all and became the soulless, mechanical slaves of the C'tan, culling the sentient lifeforms the C'tan now craved as sustenance in the terrible "Red Harvests."With the Necrontyr destroyed and the terrible new cybernetic species called the Necrons born, the C'tan began the war against the Old Ones once more with their legions of undying warriors, the cosmic confrontation that would later become known to the Aeldari as the War in Heaven.To combat these terrible foes, the Old Ones created new warrior races to battle for them, including the Aeldari, the Rashan, and the K'nib. According to later Aeldari legend, the paradise the Old Ones had created for their "Younger Races" was desecrated by the C'tan, whom the Aeldari knew as the "Yngir." During ancient times, the Aeldari learnt a great many secrets of the Warp from the Old Ones. From this knowledge, the Aeldari developed the technologies that ultimately led to their own exploiation and expansion of the Webway in later times.Knowing that the C'tan were highly vulnerable to psychic energies, the Old Ones had designed their new warrior species to be psychically linked to the Immaterium and able to use its power in destructive ways. Unfortunately, the raw emotions and collective unconscious beliefs of these new sentient species altered the psychically-active Immaterium, creating both the entities later worshipped as gods by the Aeldari and the Daemons of Chaos.The introduction of these warlike and psychic races into the galaxy had the side effect of warping the Immaterium -- the death, pain, suffering and destruction unleashed upon the galaxy during the conflict was reflected in the Immaterium, literally changing its nature into that of the current chaotic and intrinsically hostile psychic dimension called the Warp. The innocuous entities composed of psychic energy which had naturally existed in the Immaterium before the war were gradually twisted into voracious and hostile predators.By the time the Old Ones marshalled their forces, there were only four C'tan still known to be in existence, but much of the organic life in the galaxy had already been extinguished. But the C'tan empire proved unable to counter the new form of psychic warfare unleashed by the Old Ones' warrior races. Eventually, in an effort to save themselves, the C'tan and their Necron servants became devoted to severing reality's relationship to the Immaterium in order to make psychic powers useless through the deployment of blackstone-based technologies including those later known as the Cadian Pylons.Yet, even as the C'tan and the Necrons seemed to finally be driven back, the younger races' psychic instability allowed the Enslavers, a terrible species of Warp entities who could enslave the minds of psykers to create living gateways into the material world for others of their kind, to enter realspace.From cracks in reality, these denizens of the Warp sought entry into the material universe which forced the Old Ones to bring about the emergence of even more new intelligent species to defend their last strongholds. Among their creations at this time were the green-skinned, hardy Krork, who may be the ancestors of the Orks, and the technology-mimicking, orange-furred humanoids known as the Jokaero.This Enslaver Plague further devastated the population of intelligent beings in the galaxy. The Old Ones were ultimately devastated by the aftershocks of what their psychically-active creations did to the Warp, and are now believed to have either gone extinct or fled the galaxy, though the Aeldari later built an interstellar empire by extending what remained of the Old Ones' Webway into a Warp tunnel network of their own.The Enslavers' depredations also made it impossible for the Necrons to gather enough sentient beings to feed the C'tan's ever-growing hunger for life energies. At the same time, the Necrons revolted against their Star God masters and reclaimed their independence, transforming the remaining C'tan into C'tan Shards who could be used as living weapons against the Necrons' foes. Above all else, the Necron nobility now sought a way to reverse the process of biotransference and restore their organic bodies.But the galaxy had been utterly devastated and the Aeldari were clearly replacing the Old Ones as the galaxy's new power. Their civilisation left in ruins by the War in Heaven and their revolt against the C'tan, the Necrons chose to enter hibernation on thousands of "Tomb Worlds" scattered across the stars, where they would sleep in stasis tombs for tens of millions of Terran years until the Aeldari Empire had fallen and the galaxy was ripe for Necron conquest once more.