The early Zhou period is the first one for which transmitted texts exist in some abundance. The Book of Documents (ca. 900 B.C.E.) describes the Zhou conquest of the Shang as the victory of just and noble warriors over decadent courtiers led by an irresponsible and sadistic king.

Like the Shang kings, the Zhou kings sacrificed to their ancestors, but they also sacrificed to Heaven. The Book of Documents assumes a close relationship between Heaven and the king, who was called the Son of Heaven. According to the documents, Heaven gives the king a mandate to rule only as long as he rules in the interests of the people. Because the last king of the Shang had been decadent and cruel, Heaven took the mandate away from him and entrusted it to the virtuous Zhou kings. This theory of the Mandate of Heaven remained a central feature of Chinese political ideology from the early Zhou period on.

Rather than attempt to rule all their territories directly, the early Zhou rulers set up a decentralized feudal system. They sent relatives and trusted subordinates with troops to establish walled garrisons in the conquered territories. Such a vassal was generally able to pass his position on to a son, so that in time the domains became hereditary. By 800 B.C.E. there were about two hundred lords with domains large and small.

As generations passed and ties of loyalty and kinship grew more distant, the regional lords became so powerful that they no longer obeyed the commands of the king. In 771 B.C.E. the Zhou king was killed by an alliance of non-Chinese tribesmen and Zhou vassals. One of his sons was put on the throne, and then for safety’s sake the capital was moved east to modern Luoyang, just south of the Yellow River in the heart of the central plains (see Map 4.2). However, the revived Zhou Dynasty never fully regained control over its vassals, and China entered a prolonged period without a strong central authority.