Recently discovered writings in a cave in central China indicate the ebb and flow of droughts in the region, and how their effects may have shaped imperial dynasties over 500 years.

The Dayu cave, located in the Qinling mountains of Central China, holds records of seven droughts between the years 1520 and 1920. 

Researchers from the University of Cambridge along with an international team have linked the inscriptions to the arrivals of monsoons in the region. Since the Qinling mountains get 70% of their water from monsoons, their schedule greatly determines periods of drought.

Dr. Sebastian Breitenbach of Cambridge's Department of Earth Sciences says, "In addition to the obvious impact of droughts, they have also been linked to the downfall of cultures - when people don't have enough water, hardship is inevitable and conflict arises."

One inscription from 1891 reads, "On May 24th, the 17th year of the Emperor Guangxu period, Qing Dynasty, the local mayor, Huaizong Zhu led more than 200 people into the cave to get water. A fortune-teller named Zhenrong Ran prayed for rain during the ceremony." People had been coming to the cave to get water for hundreds of years.

By removing sections of the cave and analyzing the stable isotopes and trace elements, they found that certain elements and their timeframe correlated with periods of drought. Higher carbon and oxygen ratios correlated with lower rainfalls.

Facts about imperial china:

 China was ruled by dynasties from 221 BC to 1912 AD. There were ten dynasties during this period.

 Some researchers believe that China is the longest continuing civilization, with some records dating back to 6000 BC. Chinese writing is also the oldest still used written language.

 Toilet paper was invented in China in the 13th century and was used by emperors only.

Cover image: L. Tan