The probable Neolithic forebears of the Han were farming in the valleys of the Yellow River and its major tributaries as early as 6000 B.P. In the late third and early second millennia B.C.E. , a series of city-states arose in the same area; the best-documented of these, historically and archaeologically, are the Xia (centered in the Fen River valley), the Shang (centered in the western part of the North China Plain), and the Zhou (centered in the Wei River valley). Traditional historiography portrays these as successive "dynasties," but they are best seen as successively dominant city-states. By the later part of the period of Shang dominance (c. 1400-1048 B.C.E. ), written records afford us a portrayal of a highly stratified, kin-based state. The Zhou conquest of Shang in 1048 initially brought about little social change, but throughout the 800-year reign of Zhou kings, China was transformed fundamentally by the intensification of agriculture, the development of bureaucracy, the invention of iron technology, and the spread of commerce and urbanism. The latter part of the Zhou reign, referred to as the Spring and Autumn (771-482) and Warring States (481-221) periods, saw great demographic and economic expansion as well as the development of rival systems of political and social philosophy that formed the basis of Chinese intellectual life for the entire imperial period, which lasted from the unification of China by the Qin in 221 B.C.E. and continued until the overthrow of the Qing in 1911.
The 2,000 years of imperial Chinese history encompass great cultural change within a self-consciously continuous tradition. The first long-lasting imperial dynasty, the Han (206 B.C.E. -220 C.E. ), was characterized by the development of a cultural and political orthodoxy often known as Confucianism—an attempt to create a social, political, and cosmic order on the basis of highly developed ideas of individual and social morality. The breakup of the Han was followed by a period of disunity, during which Buddhism became an important cultural force; the early part of the next unifying dynasty, the Tang (618-906 CE.) witnessed the flourishing of a cosmopolitan culture, but its later years were marked by a partially xenophobic tendency. In the late Tang and Song (960-1280), the late imperial culture took shape; it was characterized by a bureaucratic ruling class, deriving its legitimacy from philosophical orthodoxy, and an economy involving an increasingly free peasantry interacting with large urban commercial, manufacturing, and administrative centers. This basic pattern was consolidated in the Ming period (1368-1644) and persisted with changes into the nineteenth century, when intensive interaction with the industrializing, expansionist Western countries led to a series of reevaluations of traditional forms and ultimately to Republican and Communist revolutions.
The overthrow of the Qing in 1911, led partly by Han ethnic nationalists, resulted in the establishment of the Republic of China. Under this banner, a series of regimes, culminating in that of the Nationalist party, or Guomindang, ruled parts of mainland China until 1949, when they retreated to the island of Taiwan, where the Nationalist party remains in power today. On the mainland of China, the Communist party, founded in 1921, gained control over the whole country in 1949, when they established the People's Republic of China and set about building a Socialist—and ultimately a Communist—society. Increasingly radical collectivist reforms culminated in the Great Leap Forward and Peoples Communes in 1958-1960, resulting in one of the largest famines in world history and in the Great Proletarian Cultural Revolution of 1966-1976. Utopian ideological and educational ideas combined with rather rigid Socialist social policy and strict Socialist economics and caused cultural stultification and economic stagnation. Beginning in 1979, the ruling Communist party initiated the Reforms, loosening the ideological grip, decollectivizing agriculture, beginning a slow transition from a planned to a market economy (by no means finished as of 1993), and expanding commercial, diplomatic, and cultural ties to foreign countries.
Both preimperiai and imperial China developed in interaction with surrounding cultures. In addition to the advanced civilization in northern China, by the end of the first millennium B.C.E. there were other centers of advanced technology in southwestern China; these were linked with more distant centers in what is now Southeast Asia. The earliest historical accounts, probably written around 800 B.C.E. , already refer to non-Chinese peoples inhabiting the four directions surrounding the Chinese center. Since that period, proto-Chinese and then Han culture has expanded, mainly southward and southwestward, to its present extent, through intermarriage, conquest, assimilation, and cultural interchange. It is certain that the Han people of central and southern China are partially descended from the non-Han peoples displaced and assimilated by the Han expansion. The cultural interchange, however, has not been entirely one-way, and southern and particularly southwestern Chinese languages, customs, religion, and other cultural elements show strong signs of influence from the non-Han inhabitants either completely displaced, as in most of the Yangzi valley, or still living in contact with the Han, as in most of the southwest.
Cultural interaction on China's northern frontiers, by contrast, has involved the ecological boundary between agriculture and herding—pastoral peoples of Central Asia have not been easily displaced or assimilated into Han society and culture. Several times in Chinese history, tribal confederations to the north or northeast of China have adopted some of the bureaucratic features of the Chinese state and used these along with their considerable military skills to conquer all or part of China and establish their own imperial dynasties. The most prominent of these have been the Toba, who established the Wei dynasty (386-534 CE) ; the Khitan, who established the Liao (907-1125); the Jurchen, who established the Jin (1115-1260), the Mongols, who established the Yuan (1234-1368); and the Manchu, descendants of the Jurchen, who ruled the Qing, the last imperial dynasty, which lasted from 1644-1911. In all of these regimes, Han people played a prominent part, but in many cases the tension between an imperial ideology, which was universalistic, and a more particular ethnic ideology of Han difference contributed to the ultimate breakup of the regime.
In both the Republic and People's Republic governments, Han leaders and officials have been overwhelmingly predominant. Leaders of the Republic, although recognizing the existence of non-Han peoples within China's political borders, based much of their legitimacy on the continuing superiority of Han civilization along with the adoption of modern technology and limited modern social forms from the West. In the People's Republic, by contrast, the multiethnic nature of China is celebrated in state ritual and protected in law. Han culture is not seen as intrinsically superior, but Han people in general are considered more advanced, because they were already moving from feudalism to capitalism at the beginning of the People's Republic, whereas many non-Han minorities were still in early feudalism or even earlier stages of the historical progression of modes of production. During the Cultural Revolution (1966-1976), this meant the imposition of modern, Socialist (in reality, Han) cultural forms on non-Han peoples; since the Reforms, Han cultural hegemony has been less emphasized, but certain aspects of assimilation continue through the education system and through various schemes for economic and social development and modernization.
In Overseas Chinese communities this process is somewhat reversed; Han people who migrate undergo various degrees of cultural assimilation to the host country. In Thailand, for example, many people of Chinese origin simply become Thai after a few generations; they remember their Chinese heritage but cease to identify with Chinese as an ethnic group. In North America, where ethnic distinctions are often based on racial distinctiveness and Chinese are easily distinguishable from Euro-Americans by sight, people usually lose most of their Chinese language and culture after a few generations but retain the emotional and cognitive group ties of ethnic identity.