Githyanki (MToF)

The warlike githyanki and the contemplative githzerai are a sundered people – two cultures that utterly despise one another. The brutal githyanki are trained from birth as warriors, while the githzerai hone their minds to a razor’s edge in their fortresses within Limbo. But before there were githyanki or githzerai, these creatures were a single species enslaved by the illithids.

Although they attempted to overthrow their masters many times, their rebellions were repeatedly crushed until a great leader named Gith arose. After much bloodshed, Gith and her followers threw off the yoke of their illithid masters, but another leader named Zerthimon emerged in the aftermath of battle. Zerthimon challenged Gith's motives, claiming that her strict martial leadership and desire for vengeance amounted to little more than another form of slavery for her people. A rift erupted between followers of each leader, and they eventually became the two races whose enmity endures to this day: the Githyanki in the way of Gith, and the Githzerai in the way of Zerthimon.

The githyanki plunder countless worlds from the decks of their astral vessels and the backs of red dragons. Feathers, beads, gems, and precious metals decorate their armor and weapons – the legendary silver swords with which they cut through their foes. Since winning their freedom from the illithids, the githyanki have become ruthless conquerors under the rulership of their dread lich-queen, Vlaakith.

Source: Mordenkainen's Tome of Foes