Background

During his reign, the Three Kingdoms (Goguryeo, Baekje, and Silla) were at war with each other, as alliances shifted and the neighboring China also experienced a change of dynasties.

Because reliable historical sources are hard to find for the Three Kingdoms period, the specifics of Mu's policies are not known.

Reign

Early in his reign, Mu attacked Silla several times. He also requested assistance from Sui dynasty of China to attack Goguryeo. Following the Goguryeo–Sui War, the Sui was replaced by the Tang dynasty in China in 618.

In 627, he attempted to recover land lost to Silla, but stopped when Tang intervened diplomatically. The same year, he sent the Buddhist monk Gwalleuk to Japan with texts on Buddhism, astronomy, history, and geography.

He formally established the Mireuksa temple in 602. He is also said to have ordered the repair of Baekje's Sabi Palace in 630, and the construction near his palace of the earliest known artificial lake in Korea. His policies in the latter half of his reign, which emphasized construction projects at the expense of national defence, are often thought to have contributed to the fall of Baekje which took place twenty years after his death.

There is reason to believe that he moved the capital of Baekje from Sabi in Buyeo County to Iksan, at least briefly. Archaeological evidence in Iksan, including tombs attributed to Mu and his wife Queen Seonhwa, appears to confirm this.

Mu retained close ties with Tang China, but Tang later allied with Silla in the wars that ultimately unified the Korean Peninsula under Silla's rule by 668.

Seodong-yo

The Samguk Yusa relates a legend regarding Mu's marriage to a princess of Silla, although historians consider it unlikely to be true, given the hostilities between the rival kingdoms. In this story, the young Seodong (Mu's childhood name) falls in love with Silla princess Seonhwa, and intentionally spreads a song about the princess and himself among the people. Thanks to this song ("Seodong-yo," or "Seodong's Song"), King Jinpyeong of Silla banishes the princess, and Mu marries her and becomes the king of Baekje.

Family

• Father: Wideok of Baekje

• Mother: Yeon Gamo

　• Brother: Jin'ni-Ō (辰爾王, ?–?) – settled in Japan and became ancestor of the Ōuchi clan and Toyota clan.

　• Queen: Lady Sataek (沙宅王后, ?–642) – daughter of Minister Sataek Jeokdeok (沙宅積德), later became the Empress Dowager Munjeong (文貞太后, 문정태후) during her son's reign.

　　• 31st king, Uija of Baekje (義慈王, 599–660) – last king of Baekje, known as Buyeo Uija (扶餘義慈) before he became king.

　• Queen: Princess Seonhwa (선화공주, 善花公主, ?–?) – daughter of King Jinpyeong of Silla.

　　• Buyeo Gyogi (扶餘翹岐, ?–?) – banished to Japan in 642.

In popular culture

• Portrayed by Kim Seok and Jo Hyun-jae in the 2005-06 SBS TV series Ballad of Seodong.

• Portrayed by Choi Jong-hwan in the 2011 MBC TV series Gyebaek.

• Portrayed by Park Chul-ho in the 2012-13 KBS1 TV series The King's Dream.