Most linguists classify all of the variations of Chinese as part of the Sino-Tibetan language family and believe that there was an original language, called Proto-Sino-Tibetan, analogous to Proto-Indo-European, from which the Sinitic and Tibeto-Burman languages descended. The relations between Chinese and other Sino-Tibetan languages are an area of active research, as is the attempt to reconstruct Proto-Sino-Tibetan. The main difficulty in this effort is that, while there is very good documentation that allows us to reconstruct the ancient sounds of Chinese, there is no written documentation of the division between proto-Sino-Tibetan and Chinese. In addition, many of the languages that would allow us to reconstruct Proto-Sino-Tibetan are very poorly documented or understood.
Categorization of the development of Chinese is a subject of scholarly debate. One of the first systems was devised by the Swedish linguist Bernhard Karlgren in the early 1900s. The system was much revised, but always heavily relying on Karlgren's insights and methods.
Old Chinese (T:上古漢語S:上古汉语P:Shànggǔ Hànyǔ), sometimes known as "Archaic Chinese," was the language common during the early and middle Zhōu Dynasty (1122 BC - 256 BC), texts of which include inscriptions on bronze artifacts, the poetry of the Shījīng, the history of the Shūjīng, and portions of the Yìjīng (I Ching). The phonetic elements found in the majority of Chinese characters also provide hints to their Old Chinese pronunciations. The pronunciation of the borrowed Chinese characters in Japanese, Vietnamese and Korean also provide valuable insights. Old Chinese was not wholly uninflected. It possessed a rich sound system in which aspiration or rough breathing differentiated the consonants, but probably was still without tones. Work on reconstructing Old Chinese started with Qīng dynasty philologists.
Middle Chinese (T:中古漢語S:中古汉语P:Zhōnggǔ Hànyǔ) was the language used during the Suí, Táng, and Sòng dynasties (7th through 10th centuries AD). It can be divided into an early period, reflected by the 切韻 "Qièyùn" rhyme table (601 AD), and a late period in the 10th century, reflected by the 廣韻 "Guǎngyùn" rhyme table. Linguists are confident of having reconstructed how Middle Chinese sounded. The evidence for the pronunciation of Middle Chinese comes from several sources: modern dialect variations, rhyming dictionaries, foreign transliterations, "rhyming tables" constructed by ancient Chinese philologists to summarize the phonetic system, and Chinese phonetic translations of foreign words. However, all reconstructions are tentative; for example, scholars have shown that trying to reconstruct modern Cantonese from the rhymes of modern Cantopop would give a very inaccurate picture of the language.
The development of the spoken Chinese languages from early historical times to the present has been complex. Most northern Chinese people, in Sìchuān and in a broad arc from the northeast (Manchuria) to the southwest (Yúnnán), use various Mandarin dialects as their home language. The prevalence of Mandarin throughout northern China is largely due to north China's plains. By contrast, the mountains and rivers of southern China promoted linguistic diversity. The presence of Mandarin in Sìchuān is largely due to a plague in the 12th century. This plague, which may have been related to the Black Death, depopulated the area, leading to later settlement from north China.
Until the 20th century, most Chinese only spoke their native local variety of Chinese. However, despite the mix of officials and commoners speaking various Chinese dialects, Nanjing Mandarin became dominant at least during the officially Manchu-speaking Qīng Empire. Since the 17th century, the Empire had set up orthoepy academies (T:正音書院S:正音书院P:Zhèngyīn Shūyuàn) to make pronunciation conform to the Qīng capital Běijīng's standard, but had little success. During the Qīng's last 50 years in the late 19th century, the Běijīng Mandarin finally replaced Nánjīng Mandarin in the imperial court. For the general population, although variations of Mandarin were already widely spoken in China then, a single standard of Mandarin did not exist. The non-Mandarin speakers in southern China also continued to use their various regionalects for every aspect of life. The new Běijīng Mandarin court standard was thus fairly limited.This situation changed with the creation (in both the PRC and the ROC, but not in Hong Kong) of an education system based on Standard Mandarin as the language of instruction. As a result, Mandarin is now spoken by virtually all people in mainland China and on Táiwān. At the time of the widespread introduction of Standard Mandarin in mainland China and Táiwān, Hong Kong was a British colony and Standard Mandarin was never used. In Hong Kong, the language of education, formal speech, and daily life remains the local Cantonese, but Mandarin is becoming increasingly influential.