Codex/Galactic History 25: Two Rivals

The Galactic History 25: Two Rivals codex entry is located within the Achievements:Datacrons section of a player's codex once it has been unlocked.

Codex entry
"This datacron holds unheard of power and knowledge collected by an ancient race. You access its power and discover writings which are clearly only one small piece of a massive galactic history:

As the Sith Empire grew in power, few Sith inspired such fear as Marka Ragnos, a tyrant who ruled for a century. His death created a power vacuum, leaving the Sith Lords Ludo Kressh and Naga Sadow vying for supremacy.

During Marka Ragnos’s funeral on Korriban, Sadow and Kressh fought a duel, each claiming he was more fit to be Dark Lord of the Sith–the then-unique title of the Empire’s ultimate ruler. But the spirit of Ragnos himself appeared, claiming a golden age of the Sith was coming. Moments later, the funeral assembly was alerted: A Republic ship had been captured.

The ship belonged to two hyperspace explorers, the siblings Gav and Jori Daragon, who had stumbled on Korriban. As the Sith Council debated the Daragons’ fate, Naga Sadow saw opportunity. The hyperspace routes leading to the Republic had been lost; the Daragons were his chance to rediscover them."