Historical Chinese phonology

Historical Chinese phonology deals with reconstructing the sounds of Chinese from the past. As Chinese is written with logographic characters, not alphabetic or syllabary, the methods employed in Historical Chinese phonology differ considerably from those employed in, for example, Indo-European linguistics.

Chinese is documented over a long period of time, with the earliest oracle bone writings dated to c. 1250 BC. However, since the writing is mostly with logographic characters, which do not directly specify the phonology of the language, reconstruction is in general quite difficult, and depends to a large extent on ancillary sources that more directly document the language's phonology. On the basis of these sources, historical Chinese is divided into the following basic periods:

Middle Chinese had a structure much like many modern varieties (especially conservative ones such as Cantonese), with largely monosyllabic words, little or no derivational morphology, four tone-classes (though three phonemic tones), and a syllable structure consisting of initial consonant, glide, main vowel and final consonant, with a large number of initial consonants and a fairly small number of final consonants. Not counting the glide, no clusters could occur at the beginning or end of a syllable.

Old Chinese, on the other hand, had a significantly different structure. There were no tones, a lesser imbalance between possible initial and final consonants, and a significant number of initial and final clusters. There was a well-developed system of derivational and possibly inflectional morphology, formed using consonants added onto the beginning or end of a syllable. This system is similar to the system reconstructed for Proto-Sino-Tibetan and still visible, for example, in the written Tibetan language; it is also largely similar to the system that occurs in the more conservative Mon–Khmer languages, such as modern Khmer (Cambodian).

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