Korean History › Three Kingdoms › Goguryeo
King Jangsu of Goguryeo
r. 413–491; capital to Pyongyang 427· Person· Rulers & states
Well documentedSolid records, physical evidence or scientific consensus.
Gwanggaeto's son, who ruled Goguryeo for 79 years, moved its capital to Pyongyang and pushed deep into Baekje.
See it on the Korean History map →What happened
King Jangsu (장수왕), whose name means 'long life,' reigned 413–491 and lived to about 97. In 414 he raised his father's stele. In 427 he moved the capital from Gungnae (Ji'an, on today's China–North Korea border) south to Pyongyang, turning Goguryeo's focus to the peninsula. In 475 his army took Baekje's capital, Hanseong, in today's Seoul, and killed King Gaero. He kept peace with both northern and southern Chinese dynasties by sending envoys to each.
Why it matters
Under him Goguryeo reached its greatest size, past the Han River, and Pyongyang became the center of the north, as it remains today.
Legacy and how we know
The Samguk sagi, Chinese histories such as the Book of Wei, and the Chungju Goguryeo Stele, found in 1979, which marks Goguryeo's reach far to the south.
Still debated
A Samguk sagi story says he sent a spy monk, Dorim, to drain Baekje with lavish building projects; it may be more legend than history.
Connections (3)
▸King Jangsu of Goguryeo erected Gwanggaeto SteleWell documented
The connection
Jangsu raised the stele in 414, the year after his father died, as both memorial and political statement. It ties his house to Goguryeo's founding myth and his father's victories, and its rules for tomb-guard households show a state organizing labor for royal rites.
When and how
414, at Goguryeo's capital Gungnae (modern Ji'an, Jilin, China), early in Jangsu's reign.
How we know
The inscription dates itself to 414, when Jangsu was king; the Samguk sagi confirms his succession the year before.
Debates and open questions
Who composed the text, and how far it was shaped to support Jangsu's own rule, is unknown.
▸King Jangsu of Goguryeo succeeded Gwanggaeto the GreatWell documented
The connection
Jangsu, Gwanggaeto's eldest son, inherited a newly enlarged Goguryeo in 413. Where his father fought mostly to the north and west, Jangsu turned south, moving the capital to Pyongyang and pressing Baekje and Silla, while keeping peace with China through diplomacy.
When and how
413, at Gungnae; Jangsu ruled until 491, far outliving his father, who died at 39.
How we know
The Samguk sagi and Chinese histories record the succession; Chinese courts granted Jangsu titles soon after.
Debates and open questions
Historians debate how much of Goguryeo's 5th-century strength was Gwanggaeto's legacy and how much Jangsu's own policy.
▸King Jangsu of Goguryeo took Hanseong from BaekjeWell documented
The connection
Jangsu's southward push peaked in 475, when he led 30,000 troops against Baekje's capital Hanseong, in today's southeastern Seoul, took it after a short siege and executed King Gaero. Baekje's court fled south and rebuilt at Ungjin (Gongju), and Goguryeo held the Han River region for about 75 years.
When and how
475, at Hanseong, near the Pungnap and Mongchon earthen fortresses in Seoul's Songpa district.
How we know
The Samguk sagi and Japan's Nihon shoki both record it; Goguryeo forts and artifacts found around Seoul, as on Achasan, confirm the occupation.
Debates and open questions
Exactly where Hanseong's palace stood, and how far south Goguryeo's control reached, are still debated.