In the 15th century, King Sejong the Great felt that the hanja were not adequate to write Korean and this was the cause of its very restricted use, so (with a likely help of the Hall of Worthies) he developed an alphabetic featural writing system known today as hangul, which was designed to either aid in reading hanja or replace hanja entirely.
Introduced in the document Hunminjeongeum, it became popular and increased literacy in Korea, but due to its suppression by the aristocratic class during the Joseon era, hangul as a national script truly took hold shortly before the fall of the Korean Empire and during the Japanese occupation of Korea.
In South Korea, the regulatory body for Korean is the Seoul-based National Institute of the Korean Language , which was created by presidential decree on January 23, 1991.
In mainland China, following the establishment of diplomatic relations with South Korea in 1992, the term Cháoxiǎnyǔ or the short form: Cháoyǔ has normally been used to refer to the standard language of North Korea and Yanbian, whereas Hánguóyǔ or the short form: Hányǔ is used to refer to the standard language of South Korea.
Roy Andrew Miller and others suggested or supported the inclusion of Koreanic and Japonic languages in the purported Altaic family (a macro-family that would comprise Tungusic, Mongolian and Turkic families); the Altaic hypothesis has since been largely rejected by most linguistic specialists.
Chinese characters arrived in Korea together with Buddhism during the pre-Three Kingdoms period.
Modern Korean descends from Middle Korean, which in turn descends from Old Korean, which descends from the language spoken in Prehistoric Korea (labeled Proto-Korean), whose nature is debated, in part because Korean genetic origins are controversial.
A relation of Korean (together with its extinct relatives which form the Koreanic family) with Japonic languages has been proposed by linguists like William George Aston and Samuel Martin.
Since the Korean War, through 70 years of separation, North–South differences have developed in standard Korean, including variations in pronunciation, verb inflection and vocabulary chosen.