The Fortress of Hijarna was the last stronghold of an ancient alien civilization. It was made of what was dubbed Hijarna stone, similar to the Hand of Thrawn on Nirauan, leading some to believe the two structures were related. It was discovered by the Fifth Alderaanian Expedition, which discovered the one thousand-year old remains of its creator's civilization, which had apparently fallen to alien invaders. Scientists speculated on the role of the fortress, with some believing it was a last-ditch defense against whatever devastated Hijarna, and others believing it was the stronghold of the invaders.