With the accession of King T'aejo's grandson, King Sejong (1418-1450 AD), the Joseon Dynasty acquired its greatest monarch and entered its greatest period of culture and creativity. King Sejong was the wisest and the most humane of the Joseon monarchs. He was a firm believer in the Confucian doctrine that cultivation of the literary arts was the path to individual virtue. Among his many achievements, King Sejong sponsored the creation of the Korean alphabet "Hangul," the first indigenous Asian language to be independently developed and written with its own phonetic script. For the first time in their history, the Korean people had a convenient and efficient system for writing their language. Chinese works were translated into Korean making them available to a wider audience. Native Korean literature, long confined to folk songs and poetry, could now be written and preserved, leading to the birth of true Korean literature. King Sejong also sponsored the publication of the Confucian Classics using a moveable, metal type machine. Characters were printed in moveable type 50 years before the Gutenberg press was invented. Literature and the arts flourished, and the 16th century became known as "the century of the scholar."
Records of the practice of Taekkyon during the Joseon Dynasty are sparse. During this time, the art reverted to its former role as a recreational and fitness activity, with the exception that it was now practiced by the general population, not the nobility. Since Confucianism was the basis for the entire government, the purely intellectual arts rose in stature and the general policy was that of "favoring the arts and despising arms." With this prevailing attitude, martial arts fell into decline.
Some warriors were even banished and forced to take refuge in Buddhist temples. Taekkyon as an art became fragmented and diffused throughout the country, and its practice continued to decline until only incomplete remnants remained, but it did not die out. It may be that, similar to Tai-chi in China, the more violent aspects of Taekkyon were disguised to preserve it from repression by despots. Although no organized instruction was available, what limited knowledge there was of Taekkyon was handed down from one generation to the next within individual families or from teacher to disciple, always in the greatest secrecy. During this time, Taekkyon was again referred to as Subak. This dismissal of the martial arts was to have severe repercussions for Korea by leaving it without adequate military leadership or trained forces to defend itself against attack.