King Jangsu of Goguryeo

King Jangsu moved the Goguryeo capital from Gungnae to Pyongyang, constructing a new fortress city. This relocation strengthened control over the southern territories and facilitated expansion into the Korean peninsula.

King Jangsu led a military campaign that captured the Han River basin from the Baekje kingdom, including the capital Hanseong. This victory gave Goguryeo control over a strategic waterway and rich agricultural lands, significantly expanding its territory.

King Jangsu established diplomatic relations with the Northern Wei dynasty of China, exchanging envoys and tribute. This alliance balanced against the Southern Dynasties and secured Goguryeo's northern borders.

King Jangsu forced the Silla kingdom to become a vassal state of Goguryeo after a series of military campaigns. Silla paid tribute and accepted Goguryeo's suzerainty, establishing Goguryeo as the dominant power in the Korean peninsula.

King Jangsu died after a reign of 79 years, the longest of any Korean monarch. His rule saw Goguryeo reach its maximum territorial extent and peak power, controlling much of Manchuria and the Korean peninsula.