Like any other Star Wars film, Star Wars: The Rise of Skywalker left viewers with many questions after they left the theater, such as where the Death Star wreckage is located and where it came from. The Death Star wreckage in The Rise of Skywalker is from the Death Star II. The Death Star II was destroyed during the Battle of Endor, in which Darth Vader and supposedly Darth Sidious were both killed. The deaths of the two Sith Lords along with the destruction of the Empire’s super weapon allowed the Rebel Alliance to seize control and form the New Republic.
When hearing the name Endor, many immediately think of the forest moon where the Rebels fought the Empire in Return of the Jedi. However, this is a common misconception due to it having the same name as one of its moons. Endor is actually a gas giant that has nine habitable moons. One of the moons was known as the Forest Moon of Endor, but beyond that, the Endor system has eight other moons: Alprezar, Fentakka, Gouuls, Hual Maka, Kef Bir, Korkar, Sharls and Vix.
In the aftermath of the Battle of Endor, pieces of the Death Star II fell into the orbit of the moon Kef Bir. The moon was primarily covered in ocean, so once the wreckage of the Death Star entered the moon’s orbit, it fell into the sea. For 31 years, the Death Star wreckage sat untouched until 35 ABY, when Rey, Poe, Finn, and Chewbacca arrived in search of the Sith Wayfinder.
Kef Bir was inhabited only by native fauna until the arrival of Company 77. Company 77 was a group of 40 First Order Stormtroopers who mutinied after being ordered to fire on innocent civilians during the Battle of Ansett Island. After mutinying, Company 77 chose to settle on Kef Bir using old Empire weapons found washed up from the Death Star wreckage.
Additionally, Company 77 domesticated the local horse-like creatures known as the Orbak. These creatures were later used in the ground assault on First Order Allegiant General Pryde's Star Destroyer. The other form of transportation used on Kef Bir were sea skiffs. These machines looked similar to the ones used by the Resistance during the Battle of Crait. Rey, Finn, and the leader of Company 77 named Jannah used these sea skiffs in order to brave the violent seas in order to reach the Death Star wreckage. While little is known about Kef Bir, it is certain that since it houses the remains of the Death Star II, it is forever interwoven with the wars that plagued the Star Wars universe.