A new report by researchers from the University of Minnesota and Lanzhou University in China in the journal Science has linked climate change, especially lack of rainfall, to the rise and fall of dynasties in China.

The scientists measured the amounts of uranium and thorium in caves in the Gansu Province to determine whether monsoons or drought characterized weather patterns throughout Chinese history. "The researchers discovered that periods of weak summer monsoons coincided with the last years of the Tang, Yuan and Ming dynasties, which are known to have been times of popular unrest. Conversely, the scientists found that a strong summer monsoon prevailed during one of China's 'golden ages,' the Northern Song Dynasty."