The “hydraulic city” of Angkor, the capitol of the Khmer Empire in Cambodia, experienced decades-long drought interspersed with intense monsoons in the fourteenth and fifteenth centuries that contributed to its eventual demise in AD 1431. The climatic evidence comes from the rings of exceptionally old tropical southern Vietnamese cypress trees.
The Angkor droughts would have impacted the sprawling city’s water supply and agricultural productivity, while exceptional flood years damaged its water control infrastructure.
Buckley, B.M., Anchukaitis, K.J, et al. Climate as a contributing factor in the demise of Angkor, Cambodia, Proc. Nat. Acad. Sci, 107(15), 6748-6752, 2010