This paper examines international relations and migrant trends in Goguryeo from the end of the 4th century to the early 5th century. In April 385, when famine broke out in Yuju and Giju, the refugees moved to Goguryeo. King Gogukyang sent 40,000 soldiers to attack Liaodong(遼東), took control of Liaodong and Hyundo Commandery, and captured 10,000 men and women alive. However, it was taken back by Morong-nong(慕容農) of Later Yan(後燕) shortly after. Morong-soo(慕容垂), the king of Later Yan, had Pyeongju jasa keep Pyungkwak(平郭), and Liaodong Taesu was also appointed. Later Yan took control of the Liaodong area. Behind the battle between Goguryeo and Later Yan, securing manpower as a military and labor resource was inherent. Morong-boo(慕容寶) established a Tributary Appointment Relationship with King Gwanggaeto(r.391~412). This recognized Goguryeo’s superiority in the eastern side of Yoha(遼河). Later Yan fell into internal chaos after passing away to Yongseong(龍城) in 397. In the process, many people died and the population declined sharply. It was for this reason that Later Yan tried to secure migrants from Goguryeo. In 400 years, Morong-sung(慕容盛) invaded Goguryeo with 30,000 troops. As a result, Sin Fortress and Namso Fortress were captured and the territory was pioneered, and 5,000 Goguryeo people were relocated to Liaoseo(遼西). Morong-sung tried to turn the tide of internal crisis with the war against Goguryeo and make up for the people who broke away from Liaoseo. Goguryeo fought back when Morong-sung(慕容熙) wasted her national power by carrying out various civil engineering projects. King Gwanggaeto took control of Sukgun castle(宿軍城) in 402 and Yeongun(燕郡) in 404. Goguryeo advanced deep into Liaoseo in its 402-404 campaign against Later Yan. In 395, King Gwanggaeto conquered the Qitan(契丹) and captured 500 men and women, and returned with 10,000 Goguryeo people who were taken away in 378. At that time, the Qitan lived in the Shiramuren River basin. The results obtained by King Gwanggaeto as a result of the Qitan expedition were 500 Qitan people, 10,000 Goguryeo people who were previously captured, and cattle, horses, and sheep. The 500 men and women of the Qitan were responsible for transporting horses and sheep from Qitan to Goguryeo. After moving to Goguryeo, they were trained as cavalry or used for various labor. In 395, King Gwanggaeto’s Qitan expedition started from Musun and Simyang. Crossing Yoha, crossing the Uimryo Mountain and Norohaho Mountains, and going northwest, it is the basin of the Rohab River and Shiramuren River. When returning, used ‘Yangpyeong road(襄平道)’, which connects from Uimryo Mountain to Liaoyang. Here, he patrolled by advancing southwest along Yeokseong Castle and the Bukpung(北豐). King Gwanggaeto sent an army in 398 to inspect the land of Sushen(肅愼) and captured 300 men and women. King Gwanggaeto achieved great results through successive expeditions and military dispatch. In particular, it was significant to secure a large number of migrants in terms of securing military and labor.
Chang-eun Jang (Thu,) studied this question.