During King Mun's reign, diplomatic ties with Tang Dynasty China were established, and many Balhae scholars went to China to study,[1] extending the influence of Buddhism and Confucianism in Balhae's governance. He also strengthened relations with Silla, which unified the Korean peninsula to the south of Balhae, overseeing the development of the trade route called Silla-road (Hangul: 신라도, Hanja: 新羅道). Balhae also increased diplomacy and trade with Japan.
King Mun moved the capital of Balhae several times (Sanggyeong and Donggyeong), stabilizing and strengthening central rule over various ethnic tribes in his realm, which was expanded temporarily. He also authorized the creation of the Jujagam (Hangul: 주자감, Hanja: 胄子監), the national academy, based on the national academy of Tang.
Although China recognized him as a king, Balhae itself referred to him as the Daeheung Boryeok Hyogam Geumryun Seongbeop Daewang (Hangul: 대흥보력효감금륜성법대왕, 大興寶曆孝感金輪聖法大王), Gadokbu (Hangul: 가독부, Hanja: 可毒夫), Seongwang (Hangul: 성왕, Hanja: 聖王) and Giha (Hangul: 기하, Hanja: 基下),[2] Although China recognized him as a king, Balhae itself referred to him as the posterity of heaven and an emperor.[3]
The tomb of his fourth daughter, Princess Jeonghyo, was discovered in 1980. The tombstone of his elder daughter, , has also been found.[4]
