The First States
In 1122 BC, a vassal of the Western marches, the Duke of Zhou, revolted against the Shang and threw them from power. In doing so he created the principle of the Mandate of Heaven, declaring that the Shang had fallen from grace and thus the gods had allowed them to be defeated. While partially a call to just rulership it also ingrained a strong flavor of "might makes right" into Chinese philosophy. The Mandate of Heaven was used by each usurping dynasty to justify its claim.
Ironically, therefore, it must be partly credited with maintaining the continuity of Chinese culture. No barbarian conqueror ever held power with any less legitimacy than the greatest of the native Chinese dynasties who had seized power in the same fashion. The fact that the forms of Chinese characters have changed but the script and language have remained fundamentally the same, speaks to the ability of the Chinese to accept even vehemently hated invaders and work with them over the course of the last 4000 years. Thus the Mandate of Heaven also partly explains why China enjoyed such unusually complete cultural domination over its conquerors.
The Zhou Dynasty is often cited as China's Golden Age. Culture and philosophy in particular flowered during this period, and wool was first manufactured in 1000 BC. Then the Shang pattern repeated; barbarian attacks forced the Zhou emperor to abandon his capital. The dynasty survived, but never really recovered. The dynasty moved to a more secure location, at Louyang in the East. 771 BC thus marks the break between the period of the Zhou emperor's greatest power, the Western Zhou Dynasty (1122 - 771 BC), and the period when the emperor gradually dwindled into a figurehead, the Eastern Zhou Dynasty (771 - 221 BC).