Gwanggaeto's deeds are carved on the largest engraved stele in the world
In 414 a Korean king named Jangsu raised a giant stone at his father's tomb and covered it with his conquests. The father, Gwanggaeto the Great, had turned Goguryeo from a battered kingdom into a leading East Asian power, and he styled himself a supreme king equal to China's emperors.
Goguryeo was in poor shape when Gwanggaeto was born in 374. Three years earlier the rival kingdom of Baekje, under its formidable king Geunchogo, had crushed Goguryeo, killed its ruler Gogukwon and sacked Pyongyang, and Baekje's reach stretched across the sea to parts of China and Kyushu. The next king, Sosurim, chose peace with Baekje, spread Buddhism through the state and reformed the army, laying the groundwork for what followed. His successor, Gogukyang, went back on the attack in 385 and 386.
Gwanggaeto took the throne on his father Gogukyang's death in 391. For his reign he picked Yeongnak, meaning everlasting joy, as its era name, and called himself Taewang, a rank matching that of an emperor. In 392 he struck Baekje with 40,000 troops and took ten walled cities, and he beat back its king Asin's counterattacks in 393 and 394, even founding nine Buddhist temples in Pyongyang in the middle of the war. In 396 he attacked Baekje's capital, Wiryeseong in present-day Seoul, by land and along the Han River. Asin submitted, handing over a prince and ten ministers.
In 399 Silla, in Korea's southeast, begged for help against Baekje and its Wa allies from the Japanese islands. Gwanggaeto sent 50,000 men, routed them and made Silla a protectorate in all but name, bringing the peninsula into a loose union under Goguryeo. To the west he defeated the Xianbei state of Later Yan and took the Liaodong peninsula, once the land of ancient Gojoseon.
His campaigns also pushed into western Manchuria against Khitan tribes, into Inner Mongolia and toward the Russian Maritime region, while control of the Han River valley gave him over two-thirds of the Korean peninsula. His long posthumous title hails him as the broad expander of the domain. He died in 412, and the stele his son set up at Ji'an, on today's border between China and North Korea, still tells his story in carved characters.
Source: Gwanggaeto the Great
