Origin of Hangul
Ledyard holds that the Koreans adopted five core consonant letters from ’Phags-pa, namely ㄱ "g" , ㄷ "d" , ㅂ "b" , ㅈ "j" , and ㄹ "l" . These were the consonants basic to Chinese phonology, rather than the graphically simplest letters (ㄱ "g" , ㄴ "n" , ㅁ "m" , and ㅅ "s" ) taken as the starting point by the "Haerye." A sixth letter, the null initial ㅇ, was invented by Sejong. The rest of the consonants were developed through featural derivation from these six, essentially as described in the "Haerye"; a resemblance to speech organs was an additional motivating factor in selecting the shapes of both the basic letters and their derivatives.
History of Korea
In 1392, General Yi Seong-gye established the Joseon dynasty (1392–1910) after a coup d'état that overthrew the Goryeo dynasty in 1388. King Sejong the Great (1418–1450) implemented numerous administrative, social, scientific, and economic reforms, established royal authority in the early years of the dynasty, and is attributed with creating Hangul, the Korean alphabet.