Long ago, before many of the worlds known in the present day were born, the illithids ruled a vast empire known to some as Nihilath. The illithid empire held many worlds and even a few planes of existence in their tentacled grip. After a thousand years of engineering, they constructed an artificial world known as Penumbra, a vast disk that circled a sun, the planet’s radius something like a hundred million miles.
This Illithid society had slaves, an evil race of beings called The Githyanki. Legends say that these beings were once human, but through selective breeding became disfigured and alien in appearance to humans. However, their intellect expanded allowing them to develop amazing mystic and psionic abilities. The Mindflayers were pleased with this race and continued to cultivate them as warriors and food throughout several empires.
As the Githanyaki grew in power and number, they eventually revolted and escaped the yoke of the Illithid empire, becoming autonomous. They formed their own empire within the Outer Planes and came to be ruled by one of their own whom they call “The Lich Queen.” The current Lich queen is a powerful and cruel wizard, who kills her powerful servants to prevent them from overthrowing her. She is the longest ruling Lich queen so far, ruling for over 1000 years. Her name is Vlaakith.
Githyanki are typically a little over 6 feet tall and around 170 pounds. Their skin is heavily yellow-tinged and has speckled coloration, while their hair is nearly absent. They are very gaunt and move efficiently.
Githyanki society was martial, with both males and females training heavily in magic and combat. Although they were loyal to each other, they were also fiercely individualistic. Raiding illithid strongholds was considered a rite of passage.
Githyanki wield silver swords that are highly prized among them and collectors, however, it should be noted that these warriors hunt down any who dare collect or wield their swords.
The Githyanki used a unique form of writing called tir’su. It was an alphabetical set of runes in which words were formed in circles instead of linearly, with the letters of a given word being linked in a ring clockwise from the top. Sentences were formed by a series of these rings. Much as runes were given a mystical significance, the Githyanki employ the tir’su when creating magical wards and symbols. It is said that these symbols are the foundation for the runic inscription used on spelljammer vessels.
Not satisfied with the destruction of the illithids alone, the war spread to any race that could potentially enslave them again. At the Pronouncement of Two Skies, the once-slave race splintered into the githyanki and the githzerai, the latter of whom was hated by the githyanki because their betrayal allowed the surviving illithids to retreat to isolated subterranean strongholds. The two races were at war ever since.
Githyanki dislike almost all other races, though they aren’t stupid and do facilitate some trade with others. They are filled with nothing but hate for the Githzerai and even more hate for the Illithid. They seem to get along famously with Red Dragons, though, for some unexplained reason.
Despite their massive cultural differences and mutual hatred of each other, the Githyanki and Githzerai are not very different from a biological standpoint. They’re both resistant to psychic powers due to long times slaving under the Illithid Empire, and they both have psychic powers of their own. The major divide between them is a shared hatred of each other due to a betrayal in the distant past.