The Hundred Year Darkness

The Hundred Year Darkness, more commonly known as the Second Great Schism, started when Jedi Knight practiced in the uses of the Force. Through their practice, the Knights learned they could shape life itself and started to experiment by creating new creatures and species. Other Jedis saw this usage of the Force as something that could be abused. The sect of Jedis, those being Ajunta Pall, XoXaan, and Karness Muur, sought to convince others about their quest for eternal life. They firmly believed that they were in the right, with their belief causing conflict within the Order. The rogue Jedi were eventually exiled, as well as their teaching.

Retreating from their homeworld of Tython, the exiled Jedis raised an army of dark side abominations to attack the other Jedis. Despite these incarnations of the dark side, the Jedi were able to push back these animalistic army and fight the Exiles directly. By the second half of the war, the Dark Jedi were outnumbered and had no chance of winning. Though they refused to give up and pooled together their power to create a Leviathans and other fearsome dark sided creatures. With this new army, the Dark Jedi used their creatures to suck the life essensce of the Jedis into themselves. However, combined effort from the Jedi led to the Dark Jedi's last stand on Corbos, with their eventual surrender on said planet.

The surviving Dark Jedis were stripped of their weapons and armor and were promptly banished, in hopes that they would see the errors in their ways. On an uncharted world, the Dark Jedi were surprised to find the humanoid Sith species on the planet. Hakagram Graush, the ruler of the Sith, was surprised by their arrival, but welcomed them eventually after witnessing their powers and technology. This would prove to be a fatal mistake as the Sith'ari under him as well as the Exiles banishing Hakagram. Using their training, the Exiles boosted their status something akin to god and became the rulers of the Sith people. As years passed, the Dark Jedi greatly accelerated the cultural development of the Sith, with the term refering to not only the species, but to the fallen Jedi Masters.