The preceding chapter has shown the rapid growth of the Western Zhou state during the first century following the conquest. The Zhou achievement in this period, known as the “Cheng-Kang Peace,” was much admired by later historians as one of the politically most accomplished periods in Chinese history. However, the issue that remains here is not so much the Zhou's ability to expand as their ability to maintain what they had already accomplished. In that regard, the Zhou appeared indeed quite incompetent. As soon as the mid-Western Zhou phase began, a new trend set in which was to drive the dynasty through a long process of gradual decline. In the hundred years after the death of King Mu (r. 956–918 bc), central control over the eastern regions increasingly weakened and the Western Zhou state faced both internal crisis and serious external threats. The problems had accumulated so enormously that in a showdown that stormed the Zhou capital in 842 bc King Li (r. 857/53–842/28 bc) was violently dethroned by the rebels and was forced into exile in the Fen River valley from which he was never to return. A dying dynasty would take much more than just the dethronement of an “unworthy” king to cure, but even the ambitious and to some extent successful policies adopted by the next king, Xuan (r. 827/25–782 bc), could serve only to postpone its final days.
What really happened in the Western Zhou state to cause the disorder and decline?