Silla attacks Goguryeo in 551 in concert with King Song (r. 523-54) of Baekje.

After conquering the upper reaches of the Han River, Silla now turns on Baekje forces and drives them out of the lower Han area.

While a tattered Baekje kingdom nurses its wounds in the southwest, Silla allies with Chinese forces of the Sui and the successor Tang (618-906) dynasties in combined attacks against Goguryeo.

The Sui emperor, Yang Di, launches an invasion of Goguryeo in 612, marshaling more than one million soldiers, only to be lured into a trap by the revered Goguryeo commander, Eulji Mundeok, who destroys the Sui forces.

Perhaps as few as three thousand Sui soldiers survive their eclipse, thus contributing to the fall of the dynasty in 618.

Tang emperor Taizong launches another huge invasion in 645, but Goguryeo forces win another striking victory in the siege of the Ansisong (An Si Fortress), forcing him to withdraw.