Primarch - Scattering of the Primarchs: The Ruinous Powers of Chaos somehow spirited the Emperor's unborn superhuman children away through the Warp in ca. 792.M30 from the gene-laboratories of what would become the Imperial Dungeons of the Imperial Palace. A massive localised Warp rift was created within the gene vaults of the palace, deep under the Himalazian (Himalayan) Mountains on Terra where the primarchs were gestating.The gestation capsules containing the Emperor's unborn sons were scattered through the Warp to Human colony planets long since lost to Mankind during the Age of Strife.It may have been at this time, when first touched by the hand of Chaos, that the first seeds of corruption were laid in the breasts of those primarchs who would eventually turn Traitor to the Emperor and His Imperium. Whether the Emperor was able to affect this outcome is unsure, but every primarch landed on ancient worlds of Humanity, planets long since lost to the light of the greater universe beyond the stars.This was a massive setback to the Emperor's plans. He had counted on His superhuman generals to lead his army of conquest out from Terra. Without them, His plans, so many millennia in the making, rested on a knife's edge. He needed an edge, something to give Mankind an advantage as they struck out against a very hostile galaxy once more.Despite this terrible setback, the Emperor was nothing if not adaptive, and He decided to move forward without the primarchs. He and the scientists of the Imperial Biotechnical Division had already used the samples of genetic material from each of His primarchs to craft the first Astartes gene-seed solar decades before, stem cell zygotes from which had been cultured genetically-engineered organs that, when implanted within a normal, adolescent Human male host, would allow that man to take on many of the physical and mental properties possessed by each primarch.The Emperor had implanted these organs into the bravest, strongest, and best young Human warriors identified among His armies whom He intended to stand by His side as the vanguard of the Great Crusade. Thus were born the Legiones Astartes, the Space Marines, and they would reconquer the galaxy for Humanity at the command of the Master of Mankind even without the initial leadership of their primarchs.Although an Astartes warrior was but a pale copy of his primarch gene-sire, the technique of implanting Human beings with extra organs allowed for a certain degree of "mass-production," and where the Emperor's 20 superhuman sons had been centuries in the making, thousands of Astartes could now be engineered and trained in the matter of a single Terran decade. These techniques provided the Emperor with the required numbers of transhuman warriors to successfully launch the Great Crusade in 798.M30.It should be noted that Adeptus Custodes genetic modifications, which are apparently derived in part from the undifferentiated primarch gene-stock, is more complex than base Astartes gene-seed, as it contains 12 more elements. The source of Custodian genetics, being only one step removed from the actual DNA of the Emperor Himself, may explain the Custodes' extremely heightened sense of kinship with the Emperor.However, the Custodian genetic code is still far simpler than each of the individual primarch genomes, even though all were derived from the same source: the undifferentiated, pure primarch gene-stock template.