The Brotherhood of Darkness, alternatively referred to as the Sith Brotherhood, the Sith Empire, or the Sith army, represented a Sith based empire. Darth Bane, a prominent Sith Lord, was a member during the Old Republic's dark age, specifically a millennium prior to the Clone Wars. While serving in this Sith military force, Bane came to the conclusion that internal conflicts and the avarice of other dark-side warriors constituted a significant vulnerability. This Brotherhood engaged the Jedi Order in a series of crusades against the Army of Light. Ultimately, this internal strife contributed to the downfall of their dark-side organization, with the Jedi Order effectively annihilating the weakened Sith.
The organization known as the Brotherhood of Darkness, which was also called the Sith Brotherhood, Sith Empire, or Sith army, functioned as an empire controlled by the Sith. It was composed of many warriors of the Sith, notably the Dark Lord of the Sith Darth Bane. This empire maintained its presence on the planet Auratera until its ultimate destruction.
One thousand years preceding the Galactic Civil War, the Brotherhood of Darkness ascended to a position of authority, establishing itself as a Sith empire. During this period, the empire's operations were centered on the planet Auratera. The Sith eventually became involved in the Jedi-Sith War in 1032 BBY, opposing the Jedi Order. During the course of this war, the Sith's inherent greed led to internal disputes, which presented an opportunity for the Jedi and the Galactic Republic to defeat the Empire, marking it as the last Sith empire of that era. The inhabitants of Auratera collaborated with the Jedi in secretly modifying official Republic records to falsely designate their system as uninhabitable. Consequently, the inhabitants and their planet became largely isolated from the rest of the galaxy, eventually severing ties with the few remaining trading partners they had following the collapse of the Sith Empire.
Darth Bane was the sole survivor of the Brotherhood's demise. He subsequently established the Rule of Two, a guiding principle that governed the remaining Sith for the subsequent millennium. Eventually, Darth Sidious, a Dark Lord of the Sith who adhered to the Rule of Two, orchestrated the destruction of the Republic from within during the Clone Wars after becoming Supreme Chancellor. He then initiated the Great Jedi Purge, which resulted in the decimation of the majority of the Jedi Order. The Galactic Empire emerged from the ashes of the Republic, solidifying Sith dominance throughout the galaxy.
The "Sith army," which is now known as the Brotherhood of Darkness, was initially mentioned in Star Wars canon in Star Wars Helmet Collection 28. Although Lucasfilm Story Group member Matt Martin has indicated that he would view it as more of an easter egg, the Brotherhood was referenced in a datascreen in the Star Wars: The Clone Wars episode "Cat and Mouse."
The Brotherhood of Darkness originally appeared in the Dark Forces: Jedi Knight comic book, which was inspired by the video game of the same name, in Star Wars Legends. It was a Sith organization founded by the Sith Lord Skere Kaan.