Chinese is the native language of approximately a billion people distributed over vast geographical areas of the world. It is the official language of mainland China and Taiwan. It is one of the two official languages in Hong Kong, where ethnic Chinese constitute more than 95 per cent of the local population. It is one of the four official languages of Singapore, where about 75 per cent of population are ethnic Chinese. It is also reasonably maintained by about 30 million Chinese scattered in other parts of the world.

Genealogically, Chinese belongs to the family of Sino-Tibetan. The earliest reliable records of Chinese in the form of jiaguwén ‘oracle bone script’ date back more than 3,000 years. Much controversy surrounds the periodization of the language since then, partly due to lack of sufficient documentary evidence on the chronological changes in the language, particularly in the pre-modern periods of its evolution, and partly due to the fact that periodization based on each of the three main components of the language, namely, phonology, grammar, and lexicon may not always be co-extensive (Peyraube 1988, 1996; S. Jiang 1994; Chan and Tai 1995). The periodization adopted in this book is first and foremost based upon changes in grammar, which may sometimes be co-extensive with phonological, and to a lesser extent, lexical development of the language. As elaborated in Lü (1985a, 1985b), Norman (1988), Peyraube (1988, 1996), Ohta (1991), Mei (1994), inter alia, each period is marked by some conspicuous innovations in syntax and morphology, the details of which need not concern us here.