<P> Towards the end of the 2nd millennium BC, the Shang were overrun by the Zhou dynasty from the Wei River valley to the west . The death of King Wu of Zhou soon after the conquest triggered a succession crisis and civil war that was suppressed by Wu's brother, the Duke of Zhou, acting as regent . The Zhou rulers at this time invoked the concept of the Mandate of Heaven to legitimize their rule, a concept that would be influential for almost every successive dynasty . The Zhou initially established their capital in the west near modern Xi'an, near the Yellow River, but they would preside over a series of expansions into the Yangtze River valley . This would be the first of many population migrations from north to south in Chinese history . </P> <P> In the 8th century BC, power became decentralized during the Spring and Autumn period, named after the influential Spring and Autumn Annals . In this period, local military leaders used by the Zhou began to assert their power and vie for hegemony . The situation was aggravated by the invasion of other peoples from the northwest, such as the Quanrong, forcing the Zhou to move their capital east to Luoyang . This marks the second large phase of the Zhou dynasty: the Eastern Zhou . In each of the hundreds of states that eventually Wikimedia Commons arose, local strongmen held most of the political power and continued their subservience to the Zhou kings in name only . Local leaders for instance started using royal titles for themselves . The Hundred Schools of Thought of Chinese philosophy blossomed during this period, and such influential intellectual movements as Confucianism, Taoism, Legalism and Mohism were founded, partly in response to the changing political world . The Spring and Autumn period is marked by a falling apart of the central Zhou power . China now consisted of hundreds of states, some only as large as a village with a fort . </P> <P> After further political consolidation, seven prominent states remained by the end of the 5th century BC, and the years in which these few states battled each other is known as the Warring States period . Though there remained a nominal Zhou king until 256 BC, he was largely a figurehead and held little power . As neighboring territories of these warring states, including areas of modern Sichuan and Liaoning, were annexed, they were governed under the new local administrative system of commandery and prefecture . This system had been in use since the Spring and Autumn period and parts can still be seen in the modern system of Sheng and Xian (province and county). The final expansion in this period began during the reign of Ying Zheng, the king of Qin . His unification of the other six powers, and further annexations in the modern regions of Zhejiang, Fujian, Guangdong and Guangxi in 214 BC enabled him to proclaim himself the First Emperor (Qin Shi Huangdi). </P> <P> Qin Shi Huangdi ruled the unified China directly with absolute power . In contrast to the decentralized and feudal rule of earlier dynasties the Qin set up a number of' commandries' around the country which answered directly to the emperor . Nationwide the philosophy of legalism was enforced and publications promoting rival ideas such as Confucianism were prohibited . In his reign unified China created the first continuous Great Wall with the use of forced labor . Invasions were launched southward to annex Vietnam . After the emperor's death rebels rose against the Qin's brutal reign in new civil wars . Ultimately the Han Dynasty arose and ruled China for over four centuries in what accounted for a long period in prosperity, with a brief interruption by the Xin Dynasty . The Han Dynasty played a great role in developing the Silk Road which would transfer wealth and ideas for millennia, and also invented paper . Though the Han enjoyed great military and economic success it was strained by the rise of aristocrats who disobeyed the central government . Public frustration provoked the Yellow Turban Rebellion - though a failure it nonetheless accelerated the empire's downfall . After the 208 AD the Han Dynasty broke up into rival kingdoms . China would remain divided until 581 under the Sui Dynasty, during the era of division Buddhism would be introduced to China for the first time . </P>

When did the ancient world end and the modern world begin