King Gwanggaeto of Goguryeo (374–413) (r. 391–413) was the nineteenth monarch of Goguryeo, the northernmost of the Three Kingdoms of Korea. His full posthumous name roughly means "Very Greatest King, Broad Expander of Territory, buried in Gukgangsang.", generally abbreviated to Gwanggaeto-wang(King-Broad Expander of Territory) or Hotaewang. He selected Yeongnak as his era name, so is called Yeongnak Taewang(Yeongnak the Great) occasionally.
Under Gwanggaeto, Goguryeo once again became a major power of East Asia, having enjoyed such a status in the 2nd century CE. Upon Gwanggaeto's death at thirty-nine years of age in 413, Goguryeo controlled all territory between the Amur and Han Rivers (two thirds of modern Korea, Manchuria, parts of Russia's Primorsky Krai, Inner Mongolia, and Eastern Outer Mongolia).
In addition, in 399, Silla submitted to Goguryeo for protection from raids from Baekje. Gwanggaeto captured the Baekje capital in present-day Seoul and made Baekje its vassal. Many consider this loose unification under Goguryeo to have been the only true unification of the Three Kingdoms.
Gwanggaeto's accomplishments are recorded on the Gwanggaeto Stele, erected in 414 at the site of his tomb in Ji'an along the present-day Chinese-North Korean border. It is the largest engraved stele in the world.
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