First Great Schism

The Great Schism was the origin of the split between the Jedi and the Sith. It occurred around 24,500 BBY.

The Sith Order was first established by dissident Jedi who believed that true power was achieved not through pensive meditation, as taught by their Jedi Masters, but through emotion. The tension between the Jedi and these dissident Dark Jedi, led by Xendor (thought by some to be the first Dark Lord of the Sith as well as the first Dark Jedi), grew until conflict erupted.

This conflict, called the Great Schism, led to the Dark Jedi being banished by the Republic. These outcasts found a new home on the distant planet of Korriban, a desolate world inhabitated by the relatively primitive but unusually Force-sensitive Sith people. Using their training in the Force, the Dark Jedi amazed the Sith and elevated themselves to god-like status on Korriban, becoming the rulers of the Sith people. As years passed, and interbreeding occurred between the Dark Jedi and the Sith, the term "Sith" came to mean not only the original inhabitants of Korriban, but also their Dark Jedi masters.

With the destruction of the original Sith Empire, for the rest of galactic history, the term Sith was more often applied to only those dark-side force-users who were the successors of Xendor and the Lords of the Sith.

It is from this rise to power and integration into Sith culture that the term Dark Lord of the Sith originated as a title bestowed upon the leader of the Sith Empire by a council of lesser Sith Lords. During the early history of the Sith Empire the coming of the prophesied savior of the Sith Order, the Sith'ari, was foretold. The Sith'ari was a perfect being who would rise to power and bring balance to the Force. According to prophecy, the Sith'ari would rise up and destroy the Sith, but in the process would return to lead the Sith and make them stronger than ever before, a striking parallel to the Chosen One of Jedi legend.