King Daemusin was the third ruler of Goguryeo, the northernmost of the Three Kingdoms of Korea. He led early Goguryeo through a period of massive territorial expansion, conquering several smaller nations and the powerful kingdom of Dongbuyeo.

Daemusin strengthened central rule of Goguryeo and expanded its territory. He annexed Dongbuyeo and killed its king Daeso in 22 CE. In 26 CE he conquered Gaema-guk, along the Amnok River, and later conquered Guda-guk. After fending off China's attack in 28, he sent his son, Prince Hodong, who was about 16 at the time, to attack the Nangnang Commandery. He also defeated the Nakrang Kingdom in northwestern Korea in 32. He destroyed Nangnang in 37, but an Eastern Han army sent by Emperor Guangwu of Han, captured it in 44.