According to the literature released for the game, the ancestors of the githyanki (the "forerunners") were once slaves to the illithids, a race of powerful telepaths who mentally enslaved sentient humanoids to work as the backbone of their vast worlds-spanning empire. It is believed these slaves were originally humans transformed through selective breeding. Eventually, these slaves developed mental resistance to their masters' mind control and, under the guidance of their leader Gith, revolted, causing the downfall of the illithid empire.
Gith, however, was not satisfied with the destruction of the illithids alone, and sought to spread the war to any race that could potentially enslave her people again. She was opposed in this endeavor by the followers of Zerthimon, who believed that such a path would lead their people to corruption and ruin. Thus, at the Pronouncement of Two Skies, the gith race fractured into the githyanki and the githzerai, the latter founding their own domain in Limbo. The githyanki hate the githzerai because their betrayal allowed the surviving illithids to retreat to isolated subterranean strongholds; the two races have been at war ever since.
After settling her people on the Astral Plane, Gith is said to have visited the Nine Hells, where she made a pact with Tiamat. In exchange for Gith's servitude, the githyanki could call upon red dragons anywhere in the multiverse as allies. Gith's advisor, Vlaakith, became the new queen of the githyanki, and all her heirs were named after her.
Dwelling in the timeless Astral Plane, the Githyanki inhabit numerous fortresses constructed from materials imported to the Astral Plane as well as cities built atop god-isles, the vast stone corpses of deceased gods. Their capital and largest city, Tu'narath, is built on the god-isle of a deceased power known only as "The One in the Void."
I mean, I know what Githyanki are, and Mind Flayers, but I guess I've been missing that particular cornerstone of D&D.
