Sometime in the period between 0 and 3 ABY, the Galactic Empire established a penal institution situated at the precipice of a canyon located on Kalaan. This detention facility served as the holding place for Luke Skywalker in 3 ABY as he awaited conveyance to Coruscant. Concurrently, General Brenn Tantor, the individual responsible for Skywalker's capture, found himself incarcerated within the same prison due to his insubordination in refusing to execute a massacre at a refugee camp shortly following Skywalker's capture on Abridon.
Brenn Tantor in his outdoor cell.
However, Tantor experienced a rescue operation orchestrated by his loyal soldiers, who facilitated his defection to the Rebel Alliance. In an effort to ingratiate himself with the Rebels, Tantor, along with his stormtroopers, launched an assault on the prison, liberating Skywalker. Additionally, they commandeered the Tracked Mobile Base, which was stationed at the prison. Subsequently, Tantor, Skywalker, and the stormtroopers journeyed to Tyr Taskeen's base, where they were evacuated to a waiting fleet.