Long ago, before the rise of the Imperium or the mergence of Mankind into the galaxy, the Eldar had established a mighty civilisation that spanned many planetary systems. Their huge cityships and craftworlds, wast ornate palaces floating between star systems, traded new knowledge and goods. Learning, enlightenment and reason flourished, the Eldar enriched the galaxy and looked for new worlds to make their own and new challenges to meet.
One challenge they took up was the complete mastery of warpgate technology. The Eldar, adopted, and refined and perfected the ancient Slaan knowledge of the warp and its movements. They established a network of wormhole tunnels through warpspace, linking gates aboard their craftworlds, planets and smaller spaceships. It was possible for an Eldar to walk from one planet to another, across hundreds or thousands of light-years of real space. THe warpgates bound the Eldar together as a single civilization, stretching across their space and, or so it was theorized, backwards and forwards in time. The Eldar, fearful of the consequences, never experimented with the temporal aspect of the warpgates.
Their studies did, however, bring them an understanding of the link between the warp and psychic power. In making this conceptual leap the Eldar also discovered the power of Chaos, in all its seductive glory. The Eldar, for all their apparent culture, had never encountered its like. Some turned from the warp with disgust when the corrupting nature of Chaos and its effects on reality became evident, but others responded with new vigour. The manifestations of Chaos - spread like wildfire through the Eldar, carried to further worlds by tainted individuals with access to the warpgates. In the space of a single generation, the Eldar paused in their quest for enlightenment and chose the darker path into the service of Chaos.
There were Eldar who were untouched by Chaos, and they retreated to the cityships and the larger craftworlds, where the more adventurous and vital members of the race had always lived. THe insanity of Chaos had no foothold or appeal aboard the vast ships. The warpgates to the infected Eldar worlds were closed and locked. The cityships were absorbed into the larger craftworlds, and all drifted into the depths of space, lifeboats and seedpods for the Eldar race.
The planetary Eldar that remained sank wholeheartedly into the dark worship of the Chaos Powers. A racial madness had taken hold throughout Eldar space, an insanity that had only one end. In a mindless psychic orgy every Eldar planet perished in a single night. The death screams of the Eldar echoes across the warp, and coalesced into a single, mighty shout. On every planet Eldar corpses twitched in the mindless dance of Chaos and crumbled to dust.
The dead Eldar, however, were not gone. Their spirits had merged with the warp and merged in a horrifying manner. Their death-shout became a howl of joy and release. Slaanesh, the Lord of Pleasure, master of unbridled depravity, was born from the dark side of the Eldar nature. The psychic pain of the Eldar's racial death and Slaanesh's birth convulsed the warp; the warpstorms around Earth were blown away, and the warp rippled into new patterns.
The last of the Eldar drifted into the long night between the stars. The racial memory of their former glory and nobility sustained them, while the downfall of the race filled them with self-disgust and bitterness. The Eldar had come face-to-face with their darkest desires and had been founf wanting.
For the Eldar, Mankinf is a reminder of what happened long age. Humanity is treading the same path towards the darkness of Chaos, a crude mirror of the Eldar's own disgrace. The Eldar have grown since, accepting and holding in the check the Chaos that lurks within their hearts, a delicate balancing act that they have at last mastered.
Mankind rushes toward the fate of the Eldar, but without the ability to preserve itself in any form. All the signs are there to be read: Humanity's moral leprosy of Chaos worship. its rising number of emergent pskers, its luct for universal power, and its fragile, failing Emperor.
The Black Library
Much of the Eldar's ancient knowledge and culture was lost during the flight from Chaos. The craftworlds became the sole repository of Eldar wisdom, and this fragmented as the Eldar nations drifted apart, Craftworlds were lost over the millennia, and Eldar knowledge vanished with them.
A single source of Eldar knowledge has reamined untouched and inviolate since their Fall. Aboard a single, dark craftworld, far beyond the boundaries of the Imperium, is the Black Library of Chaos. Here are collected all the tomes, books, and codices describing the Eldar studies of the warp. The forbidden lore of the Black Library describes the blandishments, influences, forms, creatures, perils, promises, and horrors of Chaos. Enclosed within a nearly impenetrable psychic barrier, the Black Library is watched and maintained by the Guardian-Scribes; they collate and transcibe the knowledge of the Library, a task that they have carried out since the Fall of the Eldar. They also mainstain a hawk-like watch over their charges, the books; these are dreadful repositories of secret powers and must be monitored at all times.
The existance of the Library is known to only a few of the Eldar, and entry within its walls allowed to even fewer individuals. The Library's 'mind' defends itself against the weak who would misuse its knowledge by refusing entry to all except those who have acknowledged and tempered the Chaos within themselves. The immature, who are still vulnerable to the promises and seductions of Chaos, find that they are unable to pass through its gateway. As a result few have seen within the Library or read of its books. Only two groups come and go at will: the Human Illuminati and the Solitaires of the Eldar Harlequins.