 <unk> became common in northern China in the early 17th century because of unusually dry and cold weather that shortened the growing season — effects of a larger ecological event now known as the Little Ice Age . Famine , alongside tax increases , widespread military desertions , a declining relief system , and natural disasters such as flooding and inability of the government to properly manage irrigation and flood @-@ control projects caused widespread loss of life and normal civility . The central government , starved of resources , could do very little to mitigate the effects of these calamities . Making matters worse , a widespread epidemic spread across China from Zhejiang to Henan , killing an unknown but large number of people . The deadliest earthquake of all time , the Shaanxi earthquake of 1556 , occurred during the Jiajing Emperor 's reign , killing approximately 830 @,@ 000 people . 
