Same-Phoneme Group Analysis: A New Method for Reconstructing the Phonological Continuum of Tungusic, Korean, and Japanese in Early Records

This study introduces a new comparative linguistic methodology, Same-Phoneme Group Analysis, for reconstructing the phonological continuum among Tungusic, Korean, and Japanese languages as reflected in ancient records such as Kojiki and Nihon Shoki.Traditional historical linguistics relies on one-to-one phoneme correspondences, which fail to capture the fluid sound alternations and dialectal interchangeability characteristic of pre-literate Northeast Asian languages. In this method, phonemes are classified into interchangeable phoneme groups—for example, vowel groups {i, e}, {a, o}, and {u, w, y}, and consonant groups such as {m, p, b, w, v, f} or {r, l, n, y}.By comparing words across Tungusic, Manchu, Korean, and early Japanese sources according to these group structures rather than exact phonetic identity, the analysis reveals underlying patterns of phonological variation and continuity. Applying this framework to royal and clan names written with mixed on and kun readings in the early Japanese chronicles demonstrates that these transcriptions preserve a shared sound structure rather than isolated phonetic forms.Consequently, the study reinterprets the linguistic history of East Asia as a phonological continuum—a wide-ranging areal network of mutually convertible sound systems extending from the Amur region to the Japanese archipelago. The Same-Phoneme Group Analysis provides a new perspective for historical-comparative linguistics, enabling systematic reinterpretation of early East Asian lexical correspondences, phonetic transcriptions, and areal diffusion patterns that conventional comparative methods have failed to explain.