Middle Chinese phonology is mainly based on the information from the phonological system of the Qièyùn 切韻, a rhyme dictionary compiled in 601. The literary standard represented by the Qièyùn and its later revisions served as the rhyming standard for centuries, even up until modern times. The phonological system of the Qièyùn as a rhyming standard is closely related to the imperial examination. In a country with many local dialects, a national standard had to be established for the examination. Once the phonological standard was established, it became almost impossible to change it in the context of the imperial examination for both the examinees and examiners. It is worth noting that unlike the phonology of Old Chinese, the categorical information of Middle Chinese has been thoroughly analyzed in the rhyme tables. The reconstruction of the phonetic values of the phonology of Middle Chinese was started in the early twentieth century by Western scholars, spearheaded by Bernard Karlgren’s Études sur la Phonologie Chinoise (1915–1926). In all the proposals of phonetic reconstructions, the categorical contrasts of the Qièyùn are strictly preserved and the phonological labels of the rhyme tables are consistently followed.

Starting in the Tang dynasty, as an effort by the government, decisions were made to merge rhyming categories. The final result can be found in the Guǎngyùn, in which each rhyme is labeled either as dúyòng 獨用 ‘independent’ or some tóngyòng 同用 ‘shared’. The simplification of the rhyming categories of the Qièyùn represents the realization of the impractical details of said rhyming categories. Middle Chinese phonology, as a period of the Chinese language, also has its variants in time and space. It has been proposed that Middle Chinese should be further divided into two periods: Early Middle Chinese and Late Middle Chinese. The former is represented by the Qièyùn 切韻 and the latter by early rhyme tables such as the Yùnjìng 韻鏡. The Shēngyīn Chànghè Tú by Shào Yōng 邵雍 (1011–1077) displays a number of phonological characteristics which seem to be “Mandarin”, although it is still not clear whether the Shēngyīn Chànghè Tú is a description of Shào Yōng’s home dialect, the Luoyang dialect, or a system including the characteristics of both.

In 1368 the Ming dynasty began its rule. The location of the capital changed from Dadu (modern Beijing) to Nanjing (1368–1421), and later back to Beijing (1421–1644). Because of the different locations of the capital and other issues related to the standard pronunciation, the question of which dialect served as a foundation for the standard pronunciation has been a point of strong interest to researchers. In 1375 the rhyme dictionary Hóngwǔ Zhèngyùn 洪武正韻 was compiled at the order of the first Ming emperor. In the fifteenth century Korean scholars made a great effort to transcribe this prestigious phonological work into the newly invented Hangul spellings. The result was the Hóngwǔ Zhèngyùn Yìxùn 洪武正韻譯訓, finished in 1451 with a revision in 1455. The Hóngwǔ Zhèngyùn Yìxùn provides phonetic values for the phonology of the Hóngwǔ Zhèngyùn. The Xīrú Ěrmù Zī 西儒耳目資 ‘An Aid to the Eyes and Ears of Western Literati’ of 1626 by Nicolas Trigault (1577–1628) represents one of the earliest efforts to transcribe an entire Chinese phonology into an alphabetical system without referring to Chinese rhyme works.

The Manchus formed the Qing dynasty in 1636 and became the rulers of China in 1644. In the Qing dynasty there was also an effort by the government to establish a phonological standard, and in pursuit of this goal the Yùdìng Pèiwén Yùnfǔ 御定佩文韻府 was published in 1711. This rhyme dictionary did not follow the Hóngwǔ Zhèngyùn of 1375. Instead it followed the earlier rhyming tradition, the Píngshuǐ Yùn 平水韻 of the thirteenth century. The Imperial Era of China ended in 1911. The capital of the Republic of China started in Nanjing. It switched to Beijing and then back to Nanjing. The colloquial pronunciation of the then Beijing dialect was well transcribed in the Yǔyán zì ěr jí 語言自邇集 Yü-yen tzǔ-êrh chi: A Progressive Course Designed to Assist the Student of Colloquial Chinese by Thomas Francis Wade (1818–1895). In 1949, after the Chinese civil war, the capital of the People’s Republic of China was established in Beijing. The Beijing dialect was chosen as the base for the national standard pronunciation during both time periods.

The introductory chapter mainly provides two kinds of information. One is the explanation of some basic terminologies used in the traditional study of Chinese phonology. The other is various source materials that are used in the study of Chinese historical phonology. These two kinds of information are very much interrelated. Due to the logographic nature of the Chinese writing system, the study of a historical sound system is a rather difficult task. Despite such difficulty, Chinese scholars have been diligently analyzing the phonological system of Chinese for more than fifteen hundred years. In the long history of Chinese scholarship, the achievements of phonological studies are represented by a large number of terminologies. Since all these achievements were made at the absence of an alphabetical spelling system, what has been achieved by and large is the collection of categorical information, such as how many tones, how many initials, and how many different categories of finals a given dialect or standard has. The terminologies are the keys to understanding traditional phonology. They are frequently used in the phonological studies for all periods: Old Chinese, Middle Chinese, Old Mandarin, and even Modern Mandarin.

Quite systematic transliterations of Chinese can be found in the Persian documents created in the Persian part of the Mongol Empire (1256-1353). A fairly large number of the transcriptions of Chinese words can be found in two books. One is Rashid al Din’s History of China, which is a part of his world history (Tārīkh-i Chīn az Jāmiʻ al-Tavārīkh). The other is Mài Jué 脈訣, which is an annotated translation into Persian of a Chinese medical treatise in verses. The transcriptions were based on the colloquial Chinese pronunciation, and thus they can provide us the phonetic information that cannot be retrieved from the Chinese categorical materials. The Persian transcriptions of Mài Jué show very interesting variations of individuals’ spoken language. Some are quite close to the features of the capital dialect, and some only show certain features of the Mandarin dialect while maintaining obvious non-Mandarin features of the southern dialects. Thus, it is very possible that in the process of the translation project, the translator introduced dialectal features into their pronunciation of Mandarin.