The quest for Exegol represents the undertaking by Supreme Leader Kylo Ren of the First Order around 35 ABY, aiming to solidify his dominion across a large portion of the galaxy. This endeavor was spurred by a puzzling transmission carrying the vengeful tone of the long-deceased Galactic Emperor Sheev Palpatine, also known as the Sith Lord Darth Sidious. Unbeknownst to most, Sidious's essence had cheated death by occupying a clone body located on the planet Exegol within the Unknown Regions, where a secret society of Sith devotees attended to him.
Around 35 ABY, a strange transmission echoed throughout the galaxy, utilizing the voice of the late Galactic Emperor Sheev Palpatine, secretly the Sith Lord Darth Sidious, to deliver a threat of retribution. This transmission was interpreted as a direct challenge to Supreme Leader Kylo Ren's power, who perceived its origin as a danger to his freshly acquired authority. Driven to eradicate any potential threats, Ren promptly shifted the First Order's focus from the ongoing First Order-Resistance War towards locating and eliminating the source of the broadcast.
Unknown to Ren, and even to the highest ranks of the First Order, Sidious had secretly been brought back to life within a clone body on Exegol. There, nestled deep within the impassable Unknown Regions, the ousted Emperor lived in isolation, cared for by a group of Sith loyalists who continued the Sith traditions and aimed to realize the former Emperor's schemes for a new Sith Empire.
As Ren consolidated his control over the First Order, he discovered Snoke's bases, his predecessor, and came to the realization that even the previous Supreme Leader had been a pawn of some greater power. Motivated by the teachings of his former master, Ren concentrated intensely on the search, fueled by a burning desire for answers to ensure his subservience to no one. Ren's efforts eventually guided him to the Outer Rim planet of Mustafar, once home to his grandfather, the Sith Lord Darth Vader. Leading a team of stormtroopers, Ren and his soldiers engaged in combat against the Alazmec of Winsit, a Sith cult originating from the Corvax Fen plain who venerated Vader, all to reach the remains of Fortress Vader. Surpassing his stormtroopers, Ren reached the ruins and encountered the Eye of Webbish Bog, who bestowed upon him Vader's wayfinder.
With the name "Exegol" suddenly implanted in his mind, Ren utilized the wayfinder to navigate to Exegol, seeking to confront Sidious and uncover the power he believed was hidden on the planet. There, Ren discovered the Sith Eternal cult and encountered the spectral Emperor, learning about his continued existence. The Emperor proposed to Ren the command of the Sith Eternal's fleet, the Final Order, on the condition that he eliminate the Jedi apprentice Rey, whom he revealed to Ren as his granddaughter. Ren accepted, understanding that he had been groomed as the heir to the new Sith Empire poised to emerge from the depths of the Unknown Regions. However, the young Supreme Leader harbored no intention of serving the Sith, feeling he had sacrificed too much to be subservient once more. Instead, Ren aimed to form an alliance with Rey to jointly kill the former Emperor and govern the galaxy together.
Supreme Leader Ren held suspicions regarding Sidious's true intentions, but he believed that by merging his own military with that of the Sith Eternal, the First Order would evolve into a true Empire with himself as its Emperor. The Supreme Council initially found themselves at odds with their Supreme Leader's impulsive nature and complete dedication to the dark side, as the traditionalist First Order officers favored more conventional military strategies for conquering the galaxy. Upon Ren's return to the First Order, General Domaric Quinn voiced skepticism about the cult, labeling them as conjurers and diviners.
However, Allegiant General Enric Pryde pointed out that an alliance with the cult would exponentially increase their military resources, enhancing their forces to match the power of the former Galactic Empire. Unbeknownst to all, Pryde was a Sith Eternal operative who prioritized serving the resurrected Sidious above all else. Ren's promise of new starships and soldiers from the Unknown Regions boosted the Supreme Council's faith in him, ultimately leading them to support his alliance with the Sith Eternal. Consequently, the First Order began preparing the elite army for their final push towards galactic domination. Nevertheless, a subtle tension persisted between the highly organized military of the First Order and the mystical cultists of the Sith Eternal.
After Ren abandoned the First Order and the dark side, the Sith Lord contacted General Pryde, a veteran of the Empire, and instructed him to come to Exegol to retrieve the Sith fleet. As the Sith Eternal prepared their fleet for launch into hyperspace, the Resistance launched an invasion of the Sith stronghold during the Battle of Exegol to prevent the fleet from deploying across the galaxy and reinforcing the First Order's forces. The Sith fleet was ultimately destroyed after the Resistance received support from a mobilized fleet of civilians during the battle at Exegol. Their victory sparked a widespread rebellion against the First Order, leading to the First Order's collapse across the galaxy as its military rule disintegrated without the Sith reinforcements. The Emperor and his followers were killed by Rey when she sacrificed herself to embody the spirits of past Jedi, although Rey was revived by Ben Solo, who gave his own life for hers.