[1][2] 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.

[3] 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.

Archaeological evidence in Iksan, including tombs attributed to Mu and his wife Queen Seonhwa, appears to confirm this.

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.