Others, notably Vovin, interpret the affinities between Korean and Japanese as an effect caused by geographic proximity, i.e. a sprachbund.
The language standard of this period is based on the dialect of Kaesong because Goryeo moved the capital city to the northern area of the Korean Peninsula.
The first foreign record of Korean is the Jilin leishi, written in 1103 by a Chinese Song dynasty writer, Sūn Mù 孫穆.
The Chinese Ming dynasty Bureau of Translators compiled a Chinese–Korean vocabulary of Joseon-era Korean in the mid-16th century.
[13][14][15] The creation of the Hunminjeongeum ('The Correct/Proper Sounds for the Instruction of the People'), the original name for Hangul, was completed in 1443 by Sejong the Great, the fourth Joseon king, and promulgated in September or October 1446.
It was created so that the common people illiterate in Hanja could accurately and easily read and write the Korean language.
Yale romanization of Korean places primary emphasis on showing a word's morphophonemic structure, so it does not indicate the actual pronunciation of the day.