Either we win this war, or the Sith will, and what then will change?
Lord Hoth

The New Sith Wars, also known as the Jedi - Sith War, and known to the Sith as the War of the Fittest, The Betrayal and The Curse of Qalydon, was the name given to the thousand years of conflict between the Jedi and the Sith, which lasted from approximately 2000 to 1000 BBY. As an era, the New Sith Wars were characterized by a spectacular rise of the Sith, the decline of the Galactic Republic, and a growing militancy in the Jedi Order. The balance between the Sith and the Republic fluctuated during the period, and at several periods, especially after the pivotal Battle of Mizra, the Republic was in danger of being overwhelmed completely.