The Jedi Civil War-era Sith Empire was led by Darth Revan, and later succeeded by Darth Malak. Revan and Malak discovered the Star Forge, a large factory which ran off of the Dark Side and corrupted both Revan and Malak, and used it to generate ships and droids to fight the Galactic Republic for control of the Galaxy. Many Jedi Knights and Republic soldiers joined Revan under his banner, including Carth's mentor, Saul Karath.
Malak later betrayed Revan when the Sith Lord's flagship was attacked by several Jedi, who were accompanied by Bastila Shan. Revan was deathly injured in the attack and captured by the Jedi and Malak took control of the Empire.
Ironically, the Empire fell at the hands of the redeemed Revan, who turned Bastila back from the Dark Side of the Force and killed Malak. The Star Forge was later destroyed by the Republic fleet.