In 400, while Gwanggaeto was occupied with Baekje, Gaya, and Wa troops in Silla, the Xianbei state of Later Yan, founded by the Murong clan in present-day Liaoning, attacked Goguryeo. Gwanggaeto repulsed the Xianbei troops. In 402, Gwanggaeto retaliated and conquered the prominent fortress called 宿軍城 near the capital of Later Yan. In 405 and again in 406, Later Yan troops attacked Goguryeo fortresses in Liaodong (遼東城 in 405, and 木底城 in 406), but was defeated both times. Gwanggaeto conquered all of Liaodong. By conquering Liaodong, Gwanggaeto recovered the ancient domain of Gojoseon; Goguryeo controlled Liaodong until the mid-late 7th century.