Rain aided Mongol conquests

Genghis Khan. Photo / NZ Herald

Warm, wet weather spanning several decades helped one of history's most fearsome tyrants to conquer most of Asia and Eastern Europe and form the largest continuous land empire the world has known, a study has found.

Scientists studying ancient Siberian pine trees in central Mongolia that date back nearly 2000 years believe Genghis Khan's rise to power coincided with unusually heavy rainfall over a couple of decades which allowed the arid grasslands of the Asian steppe to flourish.

Richer, more productive pastures for the horses on which the Mongols depended for their nomadic lifestyle helped Khan's invading armies to take territory as far east as China, as far south as Afghanistan and as far west as Russia and Hungary, the researchers said.

Tree rings show that from about 1180 to 1190, just before Genghis Khan's rule, there was a drought that probably stoked the political turbulence.

The tree rings show a period between 1211 and 1225 of sustained rainfall and mild weather which coincided with the rise of Khan's empire, according to Amy Hessl of West Virginia University.

"The transition from extreme drought to extreme moisture right then strongly suggests that climate played a role in human events. It wasn't the only thing, but it must have created the ideal conditions for a charismatic leader to emerge out of the chaos, develop an army and concentrate power," Hessl said.

"Where it's arid, unusual moisture creates unusual plant productivity, and that translates into horsepower. Genghis was literally able to ride that wave."

- Independent