Sometime between 0 and 3 ABY, the Galactic Empire constructed a prison on the edge of a canyon on Kalaan. This prison was used in 3 ABY to hold Luke Skywalker while he was awaiting transport to Coruscant. At the same time, his captor, General Brenn Tantor, was imprisoned there for having refused an order to massacre a refugee camp shortly after Skywalker's capture on Abridon.
Tantor, however, was rescued by his own men, who helped him defect to the Rebel Alliance. To gain favor with the Rebels, Tantor and his stormtroopers stormed the prison and freed Skywalker. Also taking the Tracked Mobile Base, which had been parked at the prison, Tantor, Skywalker, and the stormtroopers reached Tyr Taskeen's base, where they were evacuated to a waiting fleet.