Bast Castle's past is constantly being updated more and more as information continues to surface about its story. Bast Castle is located on the planet Vjun, a very desolate planet because of the slightly acidic rain which keeps all but a very acidic moss from growing on the surface. Vjun is also steeped in the Dark Side of the Force as the result of Force-based experiments that went awry which drove almost all of the planets populous to either kill one another or abandon the planet.

Near the end of the Clone Wars, Count Dooku, leader of the Separatist forces, had taken refuge on the planet Vjun – using one of the many abandoned castles as his personal retreat. It is believed that the history of Bast Castle began when Anakin Skywalker visited the planet on a mission with Obi-Wan Kenobi to assist Yoda with his negotiations with Count Dooku. Upon arriving on the planet, Anakin could feel his Force abilities come alive because of the high resonance of the Dark Side that exists on the planet. After Anakin turned to the Dark Side and became Darth Vader, he sustained massive damage to his body and had to be encased in an iron lung in order to sustain himself. At some point after his confrontation with his former master, Vader moved in to Bast Castle in order to have a place to retreat to for meditation, training and because it was one of the few places that Vader could be outside of his life-sustaining armor for any length of time. Even though Vjun was remote and foreboding place to want to visit, Vader knew that there might be the possibility that other people would end up at his place of refuge in his absence, whether by mistake or intentionally so after moving in to Bast Castle, Vader built heavy defenses so Bast Castle could ward off any ships that attempted to enter the planet's atmosphere. In the event that someone was actually able to make it to the castle, Vader put many traps in the castle itself that only a very powerful Force user could disarm.

As the Empire grew in power a small group of rebels began their fight against the growing rule of the Emperor. As the Rebellion gained ground in its fight, the Emperor needed Vader to be in many places across the galaxy. Shortly after the Battle of Yavin, Emperor Palpatine presented to Vader the "Executor", the first in the line of Executor-class Star Destroyers, to serve as his flagship. The Emperor did this because it would allow Vader to coordinate the eradication of the Rebel Alliance and the continue the search for his newly discovered son; however, the Emperor's primary reason may have been because the "Executor" also had one of the hyperbaric chambers Vader needed to live outside of his armor, lessening the number of times he would need to return to Vjun to rest. Even though Vader was very caught up in the struggles of dealing with the Rebellion, up until the time of his redemption and death aboard the second Death Star at the Battle of Endor, Vader still managed to return to the solace of Bast Castle on occasion until his death abord the second Death Star.

After Vader's death, Bast Castle doesn't return to the spotlight of history until about six years after the Battle of Endor when a re-born Emperor Palpatine used the castle as the headquarters for his elite force of new Dark Jedi. Darkside Executor Sedriss was the first to occupy the castle, and erected a large, black statue of Vader in one of the castle's anterooms. The Dark Jedi grew in numbers. Among the disciples under Sedriss was a Dark Jedi named Kam Solusar who, about six years after the Battle of Endor, encountered Luke Skywalker and was brought back to the Light Side of the Force. Four years after that, they would all meet again on the planet Ossus where Sedriss would be killed by an ancient Jedi Master named Ood Bnar. Once Sedriss was dead, the leadership of the Dark Jedi went to his second in command, Xecr Nist. After promoting Nist to his new position, both Nist and Palpatine returned to Bast Castle to check on the interrogation of rebel pilot Major Ntthan. Right after Palpatine's arrival, he learned that Major Ntthan has broken and disclosed on which planet Leia and Han's Jedi children were being hidden. Having found the information for which he came, Palpatine returned to the anteroom and is surprised to find Nist standing in awe of the statue of Darth Vader. Taken off guard by his blatant lack of respect, Palpatine only orders Nist to have the statue removed. Nist's disobedience would prove to be fatal mistake when later Luke Skywalker and a few of his Jedi follow Nist and the Dark Jedi back to Bast Castle where a lightsaber battle ensues in the front anteroom. To save the life of one of his Jedi, Luke Skywalker knocks down the statue and kills the most of the Dark Jedi in one swoop.

Once the Dark Jedi were defeated and the Emperor was killed once and for all quiet returned to Bast Castle for many years until the builder's grandson returned. A Jedi historian, Tionne, was able to trace a story that started more than twenty years before when Darth Vader killed his former master, Obi-Wan Kenobi, aboard the first Death Star. Vader retrieved Kenobi's lightsaber from the floor and had intended to send it back to Vjun to add to his collection but left it on the Death Star when it exploded over the planet of Yavin. A group of Ugor scavengers brought much of the Death Star debris back to their system where Rebel agents found the item. It is believed that Vader later found the lightsaber and was finally able to send it here to add to his collection. Luke Skywalker decides to send a team of Jedi to Bast Castle to find and retrieve the item. Anakin Solo, Han and Leia Organa Solo's youngest son, is among the five members sent to get the lightsaber. When they arrive at Bast Castle, they find someone else is also looking for the treasured item in the abandoned castle; a magician called Orloc. Trying to beat Orloc to find the lightsaber yet not set off any of the old fortress's defenses proved a challenge to the young Jedi, who were nonetheless successful in finding the token. However, one of the members of the team steals it and a holocron and heads off to train on his own - forcing the rest of the Jedi to follow him.

Bast Castle is now a historical monument to Darth Vader and Anakin Skywalker, someone who, from a very early age, was a pivotal part of the events that have shaped this galaxy. Some of the traps, archives and secret rooms have been excavated in an attempt to find out as much as possible about the man that was Darth Vader, but only a small part of the story is known and historians keep learning more as time goes on. Hopefully, one day, we will know everything about what has brought us to this point to better understand where we are going.