Old Chinese was written with an early form of Chinese characters, with each character representing a monosyllabic word. Although the script is not alphabetic, most characters were created by adapting a character for a similar-sounding word. Scholars have used the phonetic information in the script and the rhyming practice of ancient poetry to reconstruct Old Chinese phonology, corresponding roughly to the Western Zhou period in the early part of the 1st millennium BC. Although many of the finer details remain unclear, most scholars agree that Old Chinese differed from Middle Chinese in lacking retroflex and palatal obstruents but having initial consonant clusters of some sort, and in having voiceless nasals and liquids. Most recent reconstructions also describe Old Chinese as a language without tones, but having consonant clusters at the end of the syllable, which developed into tone distinctions in Middle Chinese.
Most researchers trace the core vocabulary of Old Chinese to Sino-Tibetan, with much early borrowing from neighbouring languages. During the Zhou period, the originally monosyllabic vocabulary was augmented with polysyllabic words formed by compounding and reduplication. Several derivational affixes have also been identified. However the language lacked inflection, and indicated grammatical relationships using word order and grammatical particles.
The earliest known written records of the Chinese language were found at the Yinxu site near modern Anyang identified as the last capital of the Shang dynasty, and date from about 1250 BC. These are the oracle bones, short inscriptions carved on tortoise plastrons and ox scapulae for divinatory purposes, as well as a few brief bronze inscriptions. The language written is undoubtedly an early form of Chinese, but is difficult to interpret due to the limited subject matter and high proportion of proper names. Only half of the 4,000 characters used have been identified with certainty. Little is known about the grammar of this language, but it seems much less reliant on grammatical particles than Classical Chinese.
From early in the Western Zhou period, around 1000 BC, the most important recovered texts are bronze inscriptions, many of considerable length. Even longer pre-Classical texts on a wide range of subjects have also been transmitted through the literary tradition. The oldest parts of the Book of Documents, the Classic of Poetry and the I Ching also date from the early Zhou period, and closely resemble the bronze inscriptions in vocabulary, syntax, and style. A greater proportion of this more varied vocabulary has been identified than for the oracular period.
The four centuries preceding the unification of China in 221 BC (the later Spring and Autumn period and the Warring States period) constitute the Chinese classical period in the strict sense. There are many bronze inscriptions from this period, but they are vastly outweighed by a rich literature written in ink on bamboo and wooden slips and (toward the end of the period) silk. Although these are perishable materials, and many books were destroyed in the burning of books and burying of scholars in the Qin dynasty, other texts have been transmitted as copies. Such works from this period as the Analects, the Classic of Filial Piety, the Mencius and the Zuo zhuan have been admired as models of prose style since the Han dynasty. The Classical Chinese of such works formed the basis of Literary Chinese, which remained the written standard until the early twentieth century.
Each character of the script represented a single Old Chinese word. Most scholars believe that these words were monosyllabic, though some have recently suggested that a minority of them had minor presyllables. The development of these characters follows the same three stages that characterized Egyptian hieroglyphs, Mesopotamian cuneiform script and the Maya script.
Some words could be represented by pictures (later stylized) such as 日 rì "sun", 人 rén "person" and 木 mù "tree, wood", by abstract symbols such as 三 sān "three" and 上 shàng "up", or by composite symbols such as 林 lín "forest" (two trees). About 1,000 of the oracle bone characters, nearly a quarter of the total, are of this type, though 300 of them have not yet been deciphered. Though the pictographic origins of these characters are apparent, they have already undergone extensive simplification and conventionalization. Evolved forms of most of these characters are still in common use today.