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; reconstruction is more difficult because, unlike Indo-European languages, no phonetic spellings were used.
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:
- Old Chinese, broadly from about 1250 BC to 25 AD, when the Han dynasty came back to power after the Xin dynasty. More narrowly, reconstructed "Old Chinese" is based on the rhymes of early poetry such as the Shijing and the phonological components of Chinese characters, and is assumed to represent the language of c. 1000-700 BC. Proto-Min developed from Old Chinese.
- Middle Chinese, broadly from about the 5th century AD (Northern and Southern dynasties, Sui, Tang, Song) through to 12th century AD. More narrowly, reconstructed "Middle Chinese" is usually based on the detailed phonetic evidence of the Qieyun rime dictionary (601 AD), later expanded into "Guangyun". The Qieyun describes a compromise between the northern and southern varieties and such rhyming dictionaries were essential to write and read aloud poetry with a rhyming pattern.
- Modern varieties, from about the 13th century AD (beginning of the Yuan dynasty, in which Early Mandarin was developed) to the present. Most modern varieties appear to have split off from a Late Middle Chinese koine of about 1000 AD (although some remnants of earlier periods are still present, ex. stops without release at the end of the syllable in Hakka and Yue).