This story takes place in the Star Wars fictional universe shortly after the establishment of a tenuous peace between the re-emergent Sith Empire and the Galactic Republic,[16] 300 years after the events of the Star Wars: Knights of the Old Republic games, and more than 3,600[17] years before the events in the Star Wars films.[18][19]
The Jedi are held responsible for the success of the Sith during the devastating 28-year-long Great Galactic War (which led to the Treaty of Coruscant prior to the "cold war"), and thus choose to relocate from Coruscant to Tython, where the Jedi Order had initially been founded, to seek guidance from the Force.[18][20] The Sith control Korriban, where they have re-established a Sith Academy.[21] The game's "Return" cinematic trailer depicts the events where Korriban is re-conquered by the Sith.
During these events, a smuggler named Nico Okarr is led to his prison cell in a jail orbiting Korriban by a Jedi, Satele Shan, and her master, Kao Cen Darach. Suddenly, a Sith named Darth Malgus, and his master Vindican, along with several Sith troops, attack the base. Satele, a trooper named Jace Malcom, and Okarr escape the attack, but Darach is cut down by Malgus. Malgus then kills Vindican, who was wounded by Darach.
Ten years later, new conflicts have arisen.[18] In the "Hope" cinematic trailer, Satele and some troops destroy a Sith party that includes Malgus. Malcom, who has become the troop's commander, states that, despite the losses, there is still hope amongst even "a single spark of courage". Later in the "Deceived" cinematic trailer, however, Malgus, having appeared to survive the earlier attack albeit with a mask covering his nose and mouth, leads an army of Sith into the Jedi Temple on Coruscant, killing many Jedi including the Jedi Master Ven Zallow.
Master Satele Shan is named the new Jedi Grand Master. The game itself is set in the cold-war soon after these events, with the Jedi Order and Galactic Republic struggling to maintain their control of the core worlds while the Sith plot their downfall and the expansion of the Sith Empire. The conflict opens on many fronts and across many planets, while native factions are engaged in political struggles or civil war.
BioWare stated, prior to release, that the game would have a significant focus on the storyline. Each of the eight classes has a three act storyline that progresses as the character levels up. A collaborative effort between BioWare, Lucasfilm Games, EA and Dark Horse Comics has resulted in webcomics entitled Star Wars: The Old Republic – Threat of Peace and Star Wars: The Old Republic – Blood of the Empire, the purpose of which is to establish the backstory as the game opens and closes.