Unlike PIE (the proto-Indo-European language reconstructed by linguists), proto-Sino-Tibetan has proved very difficult to reconstruct. The Chinese spoken and written today is quite old by European standards - around two thousand years of development with ample written records. But earlier developments have proved evasive, particularly on the Tibeto-Burman side of the family.
Chinese itself is often categorized after the work of Swedish linguist Bernhard Karlgren at the beginning of the 20th century. "Old Chinese" (上古漢語; Shànggǔ Hànyǔ) was spoken during the early and middle ZhÃ¶u Dynasty (1122 BCE to 256 BCE). Available texts range from bronze inscriptions, to poetry, to the earliest known manuscript of the I Ching (Yìjīng). Part of this period encompasses the writings of the great sages, like Confucius. The phonetic elements of modern characters help give hints about how Old Chinese was pronounced. Tones had probably not yet come into the language, but heavy aspiration was used to tell the difference between similar sounds.
"Middle Chinese" (中古漢語; Zhōnggǔ Hànyǔ) was used in the 6th through 10th centuries CE (during the dynasties of Suí, Táng, and Sòng). The “ early period” can be discerned from the rhyme table known as 切韻; Qièyùn (601 AD). A “late period” is represented by the rhyme table knows as 廣韻;
Guǎngyùn (10th century). Rhyme tables were manuscripts that listed characters in their order of "rhyming" (usually because the vowels were the same), and they show which characters sounded like which other characters in common speech.
In spite of all the risks involved in reconstructing the sounds of a bygone culture from scraps of evidence, linguists are fairly certain that they have figured out how Middle Chinese was spoken. Assistance has come from the rhyming tables, and also from contemporaneous foreign transliterations, Chinese importations of foreign words, and modern dialect evolutions.
Over the centuries, Mandarin came to be spoken by the preponderance of Han Chinese. This is because the topography of China favors travel, migration and inter-mixing of ethnic cultures in a broad expanse from the northeast (Manchuria) to the southwest (Yunnan), passing through SÃ¬chuÄn. These plains provided few barriers to cultural interaction and political integration (mainly by conquest). To the west of this band of open plains lived other peoples unrelated to the Han Chinese (like Tibetans, for example, to the west of Yunnan in the South, the Siberian tribes and the Mongols in the northwest). The remaining areas of China, to the east and south towards the coast, had a different topography, divided into smaller neighborhoods by rivers and mountains. Thus the remaining 20% of the Han Chinese spoke local dialects.
The Ming dynasty in the 14th to 17th centuries, succeeded a Mongol rule (Yuan dynasty) and was ultimately replaced by the Manchurian Qing dynasty. Nanjing was made a capital city, together with Beijing ("Bei" meaning "north" and "Nan" being "south"). During this time "Nanjing Mandarin" became a "lingua franca" for most of the northern and western provinces of China. Ultimately Beijing fell to the Manchurians (1644) and Nanking followed (1662), but the influence of Mandarin continued, even with the rule of the Manchu-speaking Qing rulers. They set up their capital in Beijing. Academies were established in the hopes of training everyone to speak according to Beijing's standard for Mandarin. Beijing Mandarin replaced Nanking Mandarin as the court's language, but it was not until late in the 19th century.
Thus, Beijing Mandarin finally became the official language late in the Qing empire, but the provinces to the south and east continued with their own versions of spoken Chinese, most of which were unintelligible to the officials.
By the middle of the 20th century, compulsory education became a feature of Chinese life, not only in the People's Republic, but also in Taiwan (or the Republic of China as it was then called). Hong Kong remained an independent British protectorate, and installed no such system. Part of compulsory education was the learning of "standard Mandarin." Taiwan also adopted Mandarin as the standard for instruction. In Hong Kong and Macau, standard Cantonese was adopted officially.