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.
