Sejong - Korean King

Sejong - Korean King
Sejong - Korean King

The fourth king of the Yi dynasty of Korea, King Sejong, ruled from 1418 until his death in 1450 was one of the most famous rulers in Korean history, and one of only two to have the title “the Great.” During his reign there was stability in Korea, and also major advances in literature and the arts, in particular the introduction of a new script.

King Sejong was born on May 6, 1397, the third son of King Taejong (r. 1400–18). When he was 10 years old, he gained the title Grand Prince Chunghyeong. He ascended the throne in 1418, at the age of 21, and his oldest brother, Prince Yangnyong Taegun, was overlooked to become king because the royal family regarded him as too headstrong and impetuous and the second brother had predeceased his father.

One of King Sejong’s first moves was to secure the southern parts of Korea against attacks by Japanese pirates who were launching raids on Korean coastal villages. He did this by sending soldiers to Tsushima, where they fended off seaborne attacks.


In the north, Sejong oversaw the building of four castles and six military posts, which were built to prevent problems with the new Ming dynasty in China. He also encouraged many people from central Korea to move to the north to help build the economy of the region and ensure continued stability.

King Sejong’s greatest legacy to Korea was his introduction of the Han’gul script. The Chiphyonjon, a royal institute that conducted research on behalf of the king, introduced this new script.

The institute compiled a long series of official histories of Korea and treatises on Confucian ideas and also organized many history talks increasing the knowledge of the royal family and the nobility in the history of Korea.

With no suitable Korean script, the Koreans had been using Chinese characters or Hanja to express their language. With Han’gul, although many Chinese words remained, it was possible to have new characters that better reflected Korean pronunciation and inflexions.

The new script was purely phonetic and is believed to have developed from Sanskrit, or even Tibetan. Sejong would have likely come across these scripts while reading religious books.

Sejong statue
Sejong statue

The new script was a move heavily opposed by many scholars, but Sejong, a linguist and an autocrat, pushed for Han’gul to become accepted. This gained Sejong the title “the alphabet king.” A dictionary was published soon afterward.

In 1420 after only two years on the throne, Sejong had established the Jiphyeonjeon or “Hall of Worthies” in the royal palace in Seoul, where he persuaded many visiting scholars to remain. During his reign scholars compiled 20 major works on Korean agriculture, astronomy, history, geography, mathematics, military history, science, pharmacology, and philosophy.

Of particular note were encyclopedias of Chinese and Korean medicine. During the 1440s King Sejong himself wrote a number of books. Yongbi Eocheon Ga (Songs of flying dragons) was written in 1445 and followed two years later by Seokbo Sangjeol (Episodes from the life of Buddha).

In June 1447 he wrote Worin Cheon-gang Jigok (Songs of the moon shining on a thousand rivers), a series of poems praising Lord Buddha, and in September of that year helped with the compilation of Dongguk Jeong-un (Dictionary of correct Sino-Korean pronunciation).

In terms of justice Sejong started a process of codifying the laws. He massively reduced the amount of corporal punishment that could be inflicted and established two levels of courts of appeal by which people under sentence of death could have evidence in their trial tested before further judges, and available for inspection by the king, prior to sentencing and execution.

Sejong is also credited with the invention of the rain gauge, self-striking water clock, and the sundial. Critics of Sejong point out the pervasive nature of slavery during his reign and that he did little (if anything) to help slaves.

Some had been sentenced to slavery for criminal actions, but most had been born into slavery and lived their lives in terrible conditions either as domestic hands in the cities or as farm laborers in the countryside. In addition, Sejong continued the system of court eunuchs, who wielded much power in the extravagant court.

King Sejong married Sim On (1395–1446) of Cheongsong, later awarded the title Princess Consort Soheon (or Sohon Shimn). They had eight sons and two daughters—the first son, Munjong, would succeed, followed by his son, Tanjong, and then the second son, Sejo.

Sejong and his first concubine, Kim Shinbin (1406–65), had six more sons. With his second concubine, Yang Hyebin, he had three further sons. His third concubine gave him another son, and his fourth and fifth concubines, another two daughters. King Sejong died in 1450 and was buried at Yong Nung.

His son Munjong succeeded him. A street in central Seoul is named after King Sejong, as is the Sejong Center for the Performing Arts. He also appears on the South Korean 10,000 won banknote. From King Sejong’s older brother descend the family of Syngman Rhee, who became president of South Korea from 1948 until 1960.