Period	Year Range	How Period Developed	Period Characteristics
Old Korean	Pre‑10th century (Three Kingdoms/Silla)	Developed during early native literary efforts; writers primarily used Classical Chinese with early native transcription systems (idu, hyangch’al)	Limited surviving material (e.g., hyangga poems and idu inscriptions); phonological details are largely reconstructed by comparison with later stages; evidence of early Sinitic influences via adapted Chinese readings
Early Middle Korean	c. 10th – early 13th century	Began with the Koryo period when the political center moved from Silla, incorporating substratal elements and early loanwords	Sparse documentation with evidence from sources like the vocabulary list (Kyerim yusa) and the Hyangyak kugu’ppang medical treatise; shows transitional phonological features, Mongolian loan influences, and the early use of interlinear annotations (kugyo˘l, kakp’il)
Late Middle Korean	15th – 16th centuries	Evolved as the language became fully documented after the invention of Hangul and the standardization of writing	A rich, voluminous textual record marked by precise phonological and morphological information; standardized spellings and detailed transcriptions capturing segmentals, suprasegmentals, and articulatory features
Early Modern Korean	Early 17th – late 19th century	Emerged as a transitional phase amid socio-political disruptions (e.g., the Imjin Wars, famine, disease) that loosened traditional conventions	Marked by unstandardized orthography with variant spellings and frequent transcription errors; notable phonological shifts (reinforcement, aspiration, palatalization, spirantization, monophthongization, erosion of vowel harmony) and a trend toward simplified grammar
Contemporary Korean	Late 19th century – present	Formed through script reforms during the enlightenment period, with orthographic standards (established by 1933) aiding modernization	Reflects modern integration into global culture; ongoing changes in the lexicon, phonology, and morphology; the standardized language used in South Korea today with influences from both Western vocabulary and modern socio-economic forces

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