Mar 10, 2014 04:44 PM EDT By Staff Reporter, UniversityHerald Reporter

A new study indicates that a bout of unusually mild and rainy weather may have helped Genghis Khan expand his empire in the 13^th century, USA Today reported.

During the time Khan and his Mongolian army were creating the largest land empire in world history -- spanning nearly all of Asia -- the unprecedented weather conditions (before or since) most benefited their cavalry, used not only for transport but in warfare. Increased ground vegetation created a surplus of food for their horses as well as livestock.

"Where it's arid, unusual moisture creates unusual plant productivity, and that translates into horsepower," study co-leader Amy Hessl of West Virginia University told USA Today. "Genghis was literally able to ride that wave."

The "Pax Weather-Cana" (note: it's only being referred to that here) lasted for all of Khan's rise, from 1211 to 1225 A.D., according to the study. Hessl and fellow study author Neil Pederson of Columbia University's Lamont-Doherty Earth Observatory ascertained their data by analyzing the rings from dead pine trees.

Analysis of Mongolia's present day climate data shows more extreme drought periods than have occurred in the last 1,000 years -- a possible effect of worldwide climate change.

"Though we cannot attribute a single event to climate change, warming temperatures have stacked the deck toward (more evaporation), so even if the amount of precipitation remains the same, high temperatures will generate a more intense drought," Hessl said. "That's what we observed in the early 21st century, and based on past moisture variation in Mongolia and future predictions of warming, we would expect to see similar events in the future."

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