Silla is weaker militarily than Goguryeo, and seeks to fend off its rival through an alliance with Baekje.

By the beginning of the fifth century, Goguryeo had achieved undisputed control of all of Manchuria east of the Liao River as well as the northern and central regions of the Korean Peninsula.

At this time, Goguryeo had a famous leader appropriately named King Gwanggaeto (r. 391-412), whose name translates as "wide open land."

Reigning from the age of eighteen, he had conquered sixty-five walled towns and fourteen hundred villages, in addition to assisting Silla when the Wa forces from Japan attacked, but as Goguryeo's domain increases, it confronts China's Sui Dynasty (589-618) in the west and Silla and Baekje to the south.