Chinese history is replete with the rise and fall of dynasties, but researchers now have identified a natural phenomenon that may have been the last straw for some of them: a weakening of the summer Asian Monsoons.
Such weakening accompanied the fall of three dynasties and now could be lessening precipitation in northern China.
Results of the study, led by researchers from the University of Minnesota and Lanzhou University in China, appear in this week's issue of the journal Science.