The Castle Lands encompassed a region located across the northern steppes of the planet Alderaan. Predominantly plains, the Castle Lands also featured the Kaamos Territory, situated north of the Juran Mountains, as well as the Glarus Valley.
Killiks, a species of sentient insectoids, formerly inhabited these plains in antiquity. Before 30,000 BBY, the Killiks constructed a series of towering, castle-resembling hive mounds throughout the plains. These castles held an intricate network of egg-laying grottoes, the chambers of which were adorned with colorful mosaics crafted from stones and pebbles. The Killiks had named the settlement Oroboro, which literally translated to "our home" in their language.
Around 30,000 BBY, a race of mighty aliens identified as the Celestials displaced the Killiks from Alderaan. This action was a protective measure, as the Killiks had depleted all the natural resources of their verdant planet and were determined to exploit other worlds in a similarly voracious manner.
In 27,500 BBY, Human colonists from Coruscant made their way to Alderaan. By this point, Oroboro had long been abandoned by the Killiks, and the only remaining evidence of their existence was their desolate, petrified hive mounds. Enshrouded in enigma, the towering, deserted cities of the Killiks became recognized as the Castle Lands. Throughout the millennia of Human occupation, the abandoned hives were left untouched, serving as a symbol of the potential downfall of civilizations.
During the final days of the planet, the Castle Lands of Alderaan served as a source of inspiration and contemplation for numerous Alderaanian artists and philosophers. Some of the organic-looking monoliths were even updated with modern amenities. Although the Humans from Alderaan were not the original inhabitants of the planet, they had seamlessly integrated the Killik Castles into their own culture. In the closing decades of the Galactic Republic, the Killik region also housed animals whose wool was utilized to produce traditional Alderaanian long coats.
Similar to the remainder of Alderaan, it met its demise by the Death Star's superlaser. However, the Killiks constructed numerous mounds resembling these beyond Alderaan following their exile into the Unknown Regions, such as on their capital world Yoggoy.