A Siberian pine in Mongolia.
Image: Amy Hessl
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The Mongol hordes led by Genghis Khan carved out the largest contiguous land empire history has ever witnessed, reaching at its apex from Asia's Pacific coast to eastern Europe and down into Persia and southeastern Asia. Although conventional wisdom suggests drought may have pushed them across the steppe to conquer more bountiful lands, ancient, long-dead trees discovered in a forbidding lava field in Mongolia give evidence that unprecedented rains might actually have helped fuel their expansion.
The Mongols took the Old World by storm in the 13th century. Their invasions and expansion are often attributed to the unstable climate they experienced on the steppes, "with them preying on others because they did not have a constant set of resources," says geographer Amy Hessl at West Virginia University. "Now, we agree they experienced a variable climate. However, this idea of drought driving the Mongols to expand their territory isn't really based on any climate data from that time, but on inferences based on modern conditions there."
In 2010 Hessl was on a National Geographic–sponsored mission there with forest ecologist Neil Pederson at Columbia University's Lamont–Doherty Earth Observatory to look at the climate history of Mongolia and how climate change might affect the area's wildfire risks. Driving by the Orkhon Valley, the original seat of the Mongol empire, they saw a huge lava field that had been produced by a volcanic eruption 7,000 years ago and checked it for ancient wood. Tree rings can shed light on a region's history — fat rings suggest abundant water that promoted growth, thin ones mean years with less water and growth; the number of rings is linked with how many years a tree has lived — and the live Siberian pines they saw in the area can live about 700 years.
The researchers also took samples from dead wood in the lava field because it can be much older than any living tree there, given how the cold, dry conditions can slow decay. Pinpointing a dead tree's age can be difficult, but a unique growth pattern of fat and thin rings in a living tree might act as a "bar code" to identify wood alive during a specific period such as the 15th century. Seeing the same pattern in living and dead wood of a certain species from the same area reveals that both were alive during the same historical period. Determining the dead wood's age then involves counting back all the rings before that span of time.
All in all, the research team of U.S. and Mongolian scientists sampled 17 trees. "We felt if we got records going back 500 years, that would be fantastic," Pederson recalls. Unexpectedly, they instead discovered two samples with tree rings dating back to A.D. 658, now the longest climate record for this part of the world— and with further research, "we might be able to find tree rings going back maybe 2,000 years," Pederson adds. "We collected these samples as an afterthought when we were exhausted and sick. To find they might go back that far is unbelievable."
Surprisingly, their preliminary findings based on the tree ring data suggest the Mongol empire actually rose during a time of abundant rain. These would have turned grasslands there extraordinarily lush, enabled the Mongols to raise vast numbers of horses and other livestock. "There are actually massive wetlands in the area, and during a warm, wet period, they might have been incredibly productive," Hessl says. "There's actually quite a lot of evidence that the Mongols were practicing agriculture around there in the early 1200s, contrary to this image of Mongols as only herders and these horseback hordes."
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15 Comments
Add CommentHere's the thing, people are adventerous when they're hopeful, not when they're desperate. A people may migrate because of a drought, but not conquer an empire.
Reply | Report Abuse | Link to thisHere's the other thing; The idea that one of the most savage, and yet enlightened group of conquerors in human history became who they were because of the climate is so unutterably fatuous that it defies credulity.
Reply | Report Abuse | Link to thisTo paraphrase a character in a Woody Allen movie: If Dennis Flanagan, the founding editor of the modern Scientific American, came back from the grave and saw what is being written in the pages of his magazine, he'd never stop throwing up.
@timbo555, did you read the last two paragraphs? NOWHERE in the article is the implication that they "became who they were because of climate". Without paraphrasing, direct quotes from the article... "we just argue that it takes energy to create an empire"..."We're saying maybe climate change may have made managing the empire difficult also." Hessl says, "Exploring how they adapted might shed light on current challenges we face." So much for fatuousness, from the Latin, fool.
Reply | Report Abuse | Link to thisI love Climate Change; it's the answer for absolutely everything!!!
Reply | Report Abuse | Link to thisNo need for messy experiments, field research, or thought anymore; just say the magic words "Climate Change" and you're automatically right.
It's so much easier not to have to think anymore.
And the best part is that it can't be disproved; ergo, it must be true!!!
Unicorns and cotton candy for everyone!!!
This is a valuable contribution to a historical debate. If nothing else, it's yet another warning against relying on simplistic answers to history's great questions.
Reply | Report Abuse | Link to thisIt's like the decline of the Mayans and the drought theories: as more evidence emerges, the picture gets muddier.
The really great question is: is history deterministic? If we had absolutely all data, would we be closer to being able to say "it happened because of ....."
@Shoshin... yep, climate change, one of those variables that needs to be considered... let's see... the last ice age and its impact on human kind... and did the first Americans come by way of the "land bridge" between ice sheets or by way of the coastline, most all that evidence now underwater, so much for field research, until the next ice age... and how to interpret the evidence we now can "see" under the sands of the Sahara, rivers and lakes. And this pesky article with new evidence that extra rains may have greened the pastures of the Mongols which would certainly have helped feed their horses, key to their expansion. But unlike you it seems, I find all the new evidence, or the more precise evidence of climate change, both global and "local", thought provoking. And instead of unicorns, the mammoths and rhinoceros painted in the caves of what is now France are just as "magical" and climate change probably figures into THAT story, not that we can "prove" it; ergo, truly thought provoking... and can I have some popcorn instead of cotton candy, there is a story there too, thousands of years in the development of corn with adaptations to climates and changes in climates... and questions as to future adaptations to ongoing global warming...
Reply | Report Abuse | Link to thisCentral Asiatic history is rife with conquering nomadic movements. The Mongols, Huns and Tammerlane are just three of the better known examples. The sweep of nomadic empire is definitely climate linked; such germinating conditions can always be found in the histories, quickly giving way to the conquering surge as far as a driving force. The thousand-year period from the rise of the Roman Republic to the Genghis/Tammerlane era is noted for population migrations from all over Central Asia, Europe and indeed, the world. Rain or shine, climate/weather is woven into all those tales.
Reply | Report Abuse | Link to thisUnicorns are cool, but I only want the cotton candy if it's rainbow colored.
Reply | Report Abuse | Link to thisThese comments are MIND NUMBING!!
Reply | Report Abuse | Link to thisLargest contiguous land empire? Was it larger than the USSR and its captive nations during the Cold War?
Reply | Report Abuse | Link to thisDoes all this mean that if it starts to rain incessantly the Chinese will arise upon horseback and dominate the whole world?
Reply | Report Abuse | Link to thisOf course, it always helps to READ the article!
Reply | Report Abuse | Link to thisThe researchers caution that they are not arguing that climate was the sole or main driver of the rise and fall of the Mongol empire. "Genghis Khan was really key to uniting many tribes together and spurred them to expand in a way that's never been repeated — we just argue that it takes energy to create an empire, just as it does today, and rains may have helped provide the grass that 'powered' their horses," Hessl says.
Actually it was larger than the USSR because it almost covered all of the area the USSR (minus Finland, Baltic states and Novgorod) did plus a fair part of the Middle East and extended into China and Tibet as well.
Reply | Report Abuse | Link to thisNo because they use cars and bikes now. Besides, now that they have challenged the USA economically they see no need for war.
Reply | Report Abuse | Link to thisWhy do so many people think that starving, which makes you weak and lethargic, leads to empire building? Pretty much every empire in history was wealthy and well fed. Well fed people have a lot more energy than the starving. Too many stupid people let their bigotry influence their thought process. Science demands that we lose our bigotry and base our theories on empirical evidence. It would be nice if the zealots on every side would learn what science really is and embrace it. Barring that, they should at least have the decency to die off.
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