Balhae (698-926 CE) was established by Dae Jo-yeong, a former military general, who gathered about 8000 migrants from Goguryeo (37 BCE – 668 CE) in the area around Mount Dongmou. At its height, Balhae occupied an enormous territory encompassing the entire Korean Peninsula north of the Daedonggang, as well as Liaoning (遼寧省), Jilin (吉林省), and Heilongjang (黑龍江省) in China, and the Maritime Province of Russia. Balhae used a wide range of cultural institutions to actively cultivate an advanced civilization, leading China to praise it as the “thriving nation of the Eastern Sea.”
To effectively rule such a huge territory, Balhae had five gyeong (provinces) and moved its capital city several times. The capital cities of Sanggyeong, Junggyeong, and Donggyeong all featured impressive architecture and exquisite artwork, such as roof tiles, bricks, dragon heads, pottery, weapons, and various Buddhist sculptures.
Balhae enjoyed a vibrant exchange with Unified Silla, as well as the Tang Dynasty and Japan. Following the fall of Balhae, some of its citizens joined Goryeo (918-1392), securing Balhae’s legacy in Korean history.