The githyanki and githzerai were once one people, enslaved by the sinister mind flayers after their arrival from the Far Realm countless years ago. Their servitude eradicated much of their former culture, and the mental powers of the illithid molded their bodies over generations – strong in body and quite capable in mind as well, they were gifted with lesser psionic abilities as the result of unspeakable experiments and horrifying psychic chirurgury. These powers made them the perfect advance guard, forced to hunt down new worlds promising new and exotic chattel for their masters’ insatiable hungers.
Eventually, they grew powerful and tormented enough to pose a true threat to their masters, and slave rebellions shook the then-mighty illthid empire which knew no borders in the Underdark, and stretched across many dominions in the Astral Sea as well. The mind flayers always managed to put down their uprisings, crushing the spirits of their slaves with each new devastating defeat.
But a leader finally appeared among them, a hero named Gith, who wielded a mighty silver sword. Her inspirational strength spread like wildfire among her kind, imbuing them with the resolve to stand up one last time. All of the slaves on all of the worlds took up arms as one, and even the powerful mind flayers could not contend with their might. The empire crumbled, and what few illithid communities remain today represent only a shadow of its former power.
When Gith called for an Eternal Crusade against the mind flayers, not all of her people shared her vision. Many had lost their fighting spirit after the uprising, and had little stomach left for conflict when the victory had cost them their homes. Gith’s greatest critic was Zerthimon, who suggested that their best defense against the return of the illithids was to look within, and master the psychic power they’d inherited.
Gith allowed this dissent. She knew that she held the power to silence Zerthimon (and by extension, his followers, who would become the githzerai), but refused to take up the mantle of a tyrant after personally leading her people from tyranny. So the followers of each began to debate with each other. The debates grew into arguments, and the arguments grew into violence. An all-out civil war soon raged among them, and neither Gith nor Zerthimon could do anything to stop it.
When their feud had burned their homeland in the into uninhabitable cinders, the armies finally grew tired of fighting. They headed in different directions to find new homes, forever divided into githzerai and githyanki.
The githzerai are a monastic and introspective people, a bright reflection of their imperialistic brethren. They make their homes in monasteries in the Elemental Chaos, where they practice martial arts and hone the psychic energies inherited by their ancestors. Many believe that with discipline and study, they will someday surpass the mind flayers in mental prowess.
Githzerai, though philosophically inclined to the ideals of goodness and order, are a far cry from being pure souls. Their race still burns with hatred for their former illithid overlords, and they have no love for their former brothers, either. The githyanki are beyond redemption in the eyes of the githzerai – too many years have they stewed in their hatred, lashing out against the innocent. Any hope of healing the rift between the two peoples died long ago, with Gith.