The Nightsisters were a sect of the Witches of Dathomir who embraced the usage of dark arts within their Force-driven Magicks. The Nightsisters were originally members of other witch clans who began to utilize the dark side in defiance of the light-sided orthodoxy found in the Book of Law the governing holy text of the Dathomiri. These witches adopted a shamanistic culture that rejected the notion of "good" and "evil", and instead chose to call upon the twin energies of the Winged Goddess and the Fanged God in order to utilize their Magicks and communicate with the spirit realm. They focused extensively on the art of casting Force illusions through "illusion spells." Witches found guilty of practicing these heretical techniques were banished into Dathomir's wilderness and left for dead. However, in the final decades of the Galactic Republic's reign, the exiled witch Gethzerion used her superior powers to unite the wandering outcasts into a new clan the Nightsisters.
Operating under a revised holy text known as the Book of Shadows, these sorceresses used their powerful connection to Dathomir's untamed wilds to terrorize their fellow clans and fight for dominance over the planet. Although the witches had designs for galactic dominance, they were largely confined to their own world, as the Jedi Order maintained active interdiction of the planet. The Nightsisters themselves were divided into various competing clans of their own until approximately 32 BBY, when Clan mother Zalem attempted to use Dathomir's legendary Infinity Gate to destroy Coruscant, the capital world of the Galactic Republic. After the plot was foiled and Zalem was killed by her daughter, the numerous clans of Nightsisters were united into a single coven by the shaman Mother Talzin. During the Clone Wars, the Nightsisters came to the forefront of galactic notoriety when Talzin transformed her people into a mercenary society that trained in combat and Magick so that their services as bodyguards, assassins, and soldiers could be sold to off-world bidders.