Between 1580 and 1640, monsoon rains in China dropped to their lowest point ever in the 1,810-year period under study, resulting once more in famine and the break-down of civil society. Ming China's starving people also suffered from several horrific epidemics of as-yet-unidentified diseases.
Sensing the weakness of the Wanli Emperor, the Manchu people of northern China (Manchuria) broke away from the Empire in 1610. Eight years later, they declared war on the Ming state. The Manchus went on to gradually conquer northern China, piece by piece, over the next 25 years. They also defeated Korea's Joseon Dynasty in 1638, cutting off one of the Ming Dynasty's staunchest allies.
Further south, other problems were cropping up for the Ming. A peasant uprising in Shaanxi Province broke out in 1630, led by Li Zicheng, the "Roaming King."
Li's force included 20,000 famine-striken farmers, and his army grew with each cold, dry year. The rebels moved through Henan, Shanxi, and Shaanxi Provinces; the Ming Army was too weak to stop the peasants, some armed only with sticks.
In April of 1644, Li Zicheng led his rebels into the capital city of Beijing. When the capital fell to the peasants, the last Ming emperor, the Chongzhen Emperor, committed suicide by hanging himself from a tree in the Forbidden City.
Li declared himself the founding emperor of the new Shun Dynasty, but he was driven out of Beijing after just one month by the advancing Manchus. The Manchus took power as the Qing Dynasty, China's last. Li Zicheng died later that same year in his home province of Shaanxi.
In this case, the rains actually returned before the final death-throes of the Ming Dynasty. 1640 was a very wet year, in fact. However, it was not enough to save the Ming from the advancing armies of the Manchus and the Shaanxi peasants.
Conclusion
The historical and environmental records are aligned to a truly remarkable degree in China.
The country suffered three lengthy failures of the rains, from 860 to 930, 1340 to 1380, and 1580 to 1640. Rainfall varied throughout the rest of the nearly 2,000 years of stalagmite records examined in the study, but it never fell so low as at those three periods.
Each time the monsoons failed, China's people began to starve. After all, rice is the staple food of China, and it is a very water-dependent crop.
Soon, the peasants rose up, marched on and seized the capital, and brought the ruling emperors down. In most cases, though, military leaders from the aristocracy founded the next dynasty, not the leaders of the peasant armies.
In any case, the "Mandate of Heaven" had been revoked.
Sources
Pingzhong Zhang, Hai Cheng, et al. "A Test of Climate, Sun, and Culture Relationships from an 1810-Year Chinese Cave Record," Science 322 (November 7, 2008). Subscription required.
"Monsoon link to fall of dynasties," BBC News (November 6, 2008).
Buckley Ebrey, Patricia and Kwang-ching Liu. The Cambridge Illustrated History of China, (Cambridge: Cambridge University Press), 1999.
