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How Rain Helped the Mongols Conquer Asia

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In the early 1200s, Genghis Khan united the warring Mongolian tribes into a mobile, efficient military state. Lashing outward in all directions from their home on Central Asia's steppe, the Mongolian armies conquered a large swath of Central Asia in just a few decades. The empire continued to expand under Genghis Khan's descendants and, at its height, was one of the largest in human history, extending from Asia's Pacific coast to Central Europe.

The Great Khan is remembered as a politically savvy leader and a brilliant military tactician, but the rise of his empire, new research suggests, might have also had something to do with a stretch of unusually nice weather.

In 2010, American researchers Neil Pederson and Amy Hessl were in Mongolia's Khangai Mountains, studying the impact of climate change on the country's wildfires. As they drove past an old flow of now-solid lava left by a volcanic eruption thousands of years ago, they saw stands of stunted pine trees growing out of cracks in the lava.

Now, as any budding naturalist can tell you, the annual growth rings of many trees reflect the conditions they grew in. A long, wet growing season results in a wide ring, and a drought-stricken year means a thin ring. After you figure out the age of a tree, these growth patterns can provide a year-by-year record of what the local climate was like. Luckily for Pederson and Hessl, these patterns were written very clearly into the trunks of their Siberian pines, which were well-preserved by the cold, dry conditions of the steppe. The pair had potentially found a wooden record of climate conditions going back thousands of years.

Pederson and Hessl took samples from 17 of the trees and found that they were indeed very old. The innermost rings of some them dated all the way back to the 7th century. Since this discovery, they've gone back and sampled more than a hundred trees in the mountains and the Orkhon Valley region, where Genghis Khan established the seat of his growing empire.

Combining their tree-growth patterns with temperature reconstructions, Pederson, Hessl, and their team pieced together a picture of what the climate was like during the centuries that the Mongols conquered and ruled.

Just before Genghis Khan rose to power, Mongolia's climate was harsh, both physically and politically. The Mongolian tribes warred against each other, and the steppe was cold and stricken by drought. Amid the conflict, the researchers say, the worsening dry conditions of the land could have been an important factor in the collapse of the old order, and paved the way for centralized leadership under Genghis Khan. "What might have been a relatively minor crisis instead developed into decades of warfare and eventually produced a major transformation of Mongol politics," they write.

Then, in the early 13th century, as Genghis Khan unified the tribes, the droughts gave way to a period when the steppes were wetter and warmer than they'd ever been. "This period, characterized by 15 consecutive years of above average moisture in central Mongolia and coinciding with the rise of Genghis Khan, is unprecedented over the last 1,112 years," the researchers say. In addition to being wet, Mongolia at the time was warm, but not exceptionally hot.

In these conditions the Mongolian grasslands would have flourished, providing fuel for the Mongolian war machine. Each of Genghis Khan's mounted warriors used several horses, and the conquering armies brought herds of livestock with them for food and other resources. The dramatic shift in temperature and precipitation came at the perfect time to provide resources for rapid military mobilization and the Mongols' early expansion.

After the empire's initial spasms of growth, the tree ring and temperature data show a return to a cold, dry climate. By then, though, the Mongols had defeated several other Central Asian powers and could exploit the conquered regions instead of relying on the grass of the steppes and their local resources.

The climate shift certainly isn't the only driver of the empire's quick rise; it might have also just been coincidental, the researchers say. To flesh out the picture that the tree rings provide, the team is working on several other studies that could corroborate their ideas. Ecologist Hanqin Tian is developing models to connect the dots between the tree-ring records of weather and grass production. Biologist Avery Cook Shinneman will analyze the layers of fungal spores from animal dung that are trapped in sediment in Mongolian lakes, which could indicate the abundance of the Mongols' livestock. Meanwhile, historian Nicola Di Cosmo will comb through records from Asia and Europe looking for historical references to the climate and the strength of the Mongolian armies.

While the tree rings provide clues about the past climate and its possible influence on the rise of an empire, they also hint that another major shake-up is yet to come in Central Asia. As they did hundreds of years ago, conditions in the region have turned from wet to arid, with long, cold winters and drought-stricken summers comparable to those experienced just before Genghis Khan seized power. During the 2000s, livestock booms went bust; millions of animals died, and hundreds of thousands of displaced herders flocked to the city of Ulaanbaatar.

Those earlier droughts happened in a much cooler climate, though. Central Asia is currently warming more than the global average, and the combination of rising temperatures and droughts, the researchers warn, could mean another era of climate-spurred social and political upheaval.

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12 Solid Facts About New Hampshire's Old Man of the Mountain
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On May 3, 2003, the craggy rock face known as New Hampshire's Old Man of the Mountain tumbled to the ground in spectacular fashion. For a landmark that had been in the state's DNA for generations, its collapse was like a death in the family to some. The day after it fell, people left flowers at the base of Cannon Mountain in Franconia Notch State Park as a sort of funeral tribute, and plans were immediately launched to create a longer-lasting memorial. So what was so great about the Old Man of the Mountain, pre- and post-crumble? Read on for the stone-cold facts.

1. THANKS TO NATHANIEL HAWTHORNE, THE OLD MAN WAS ALSO KNOWN AS “THE GREAT STONE FACE.”

Although not explicitly named, it’s widely believed Hawthorne based his 1850 short story "The Great Stone Face"—which was set in an anonymous state that happens to look like New Hampshire—on the Old Man. At that time, the mountainous figure was already a tourist draw to the Granite State. Hawthorne described it as an “enormous giant, or a Titan,” with a “broad arch of the forehead,” a long-bridged nose, and having “vast lips.” Eventually Hawthorne’s nickname stuck, along with other loving titles like “Old Man” and “the Profile.”

2. THE "FACE" WAS ACTUALLY A SERIES OF LEDGES.

These granite cliff ledges, 40 feet tall and 25 feet wide, when viewed from the north at certain angles looked like a jagged face. Hawthorne corroborated this, writing in “The Great Stone Face”: “If the spectator approached too near, he lost the outline of the gigantic visage, and could discern only a heap of ponderous and gigantic rocks ... Retracing his steps, however, the wondrous features would again be seen; and the farther he withdrew from them, the more like a human face, with all its original divinity intact, did they appear."

3. HE COULD HAVE BEEN 12,000 YEARS OLD.

An 1856 postcard of The Old Man of the Mountain
Public Domain, Wikimedia Commons

The Old Man was first discovered and recorded in 1805 by road surveyors Francis Whitcomb and Luke Brooks, which put the landmark at nearly 200 years old by the time it fell. But it likely first formed when water inside cracks in the granite bedrock froze and thawed following the retreat of glaciers about 12,000 years ago. (This freezing and thawing process was what hastened its eventual collapse.) According to geologist Brian Fowler in a research report by the Old Man of the Mountain Legacy Fund, the lower ledge—or chin—of the Old Man is assumed to have fallen first. Once that support was gone, the rest of the rock fell in formation.

4. CANNON MOUNTAIN WAS SO NAMED BECAUSE IT LOOKS LIKE ANTIQUE ARTILLERY.

The Old Man jutted from a cliff in Cannon Mountain in New Hampshire’s White Mountains, within Franconia Notch State Park. Originally named Profile Mountain, it took on a new name since its granite dome resembles a cannon from select vantage points. There are even three sub-peaks, nicknamed “The Cannon Balls.”

5. SOME OF THE STRONGEST SURFACE WINDS EVER IN THE U.S. WERE RECORDED ON TOP OF CANNON MOUNTAIN.

The gusts measured 199.5 mph on April 2, 1973. While impressive, they were likely even higher since 199.5 mph was the limit of what the researchers' instruments could record at the time. The highest surface wind gust in the U.S. still belongs in-state, though, with New Hampshire's Mount Washington recording 231 mph winds in 1934.

6. A SERIES OF TURNBUCKLES AND IRON TIES WERE PLACED WITHIN ITS FACE TO KEEP IT TOGETHER.

By 1916, as it became clear the Old Man might not live forever, the first efforts to protect the rock formation were made. By the 1920s, a crack in the Old Man’s "forehead" was clearly noticeable, and residents who were worried about its safety used chains, turnbuckles, and iron ties to keep the crack from separating. Many of those metal rods used to hold the Old Man together were still attached to the mountain years later.

7. THE STATE EVENTUALLY SPENT A SMALL FORTUNE TRYING TO SAVE IT.


Julius Hall, Public Domain, Wikimedia Commons

In 1957, the New Hampshire state legislature passed a $25,000 appropriation for the necessary repairs to slow the Old Man's deterioration. These steps included quick-drying cement and steel rods meant to fill in and fortify cracks. The rocky Band-Aids were maintained every summer.

8. THE CARETAKERS’ MAINTENANCE ROUTINES WERE METICULOUS.

One longtime caretaker, Niels Nielsen, took great pains to keep the Old Man clean since 1965. Nielsen would spray bleach on the rock face and in its cracks, then carefully remove moss and lichen in an effort to prevent cracks from spreading further. He would even clean out the Old Man’s ear with a garden hoe. When Nielsen retired, he passed the job on to his son, David. The face continued to be groomed until its collapse.

9. NIELS NIELSEN SAW THE OLD MAN AS A GIFT FROM GOD.

According to Yankee Magazine, Nielsen was rather enchanted by the rock formation. “I had sailed around the world as a merchant seaman, yet I had never seen anything like the Old Man," he said. "I don’t believe anyone can be up there and not feel the presence of God."

10. BUT EVEN NIELSEN KNEW IT MIGHT FALL SOME DAY.

Nielsen was asked by Yankee what would happen if the Old Man ever fell. “The Lord put him here, and the Lord will take him down," Nielsen replied. Research concluded its collapse was natural—that the freezing-thawing process and subsequent erosion over time caused its downfall.

11. YOU CAN STILL "SEE" THE OLD MAN.


Rob Gallagher, Public Domain, Wikimedia Commons

The image of the Old Man has lived on as a state emblem since 1945, appearing on highway signs, on the back of drivers licenses, and on the reverse of the state quarter. But residents weren’t done with honoring the now-deceased rock face. At Old Man of the Mountain Profile Plaza and Historic Site in Franconia, special viewfinders and steel “profilers” at vantage points near Profile Lake offer a glimpse of what the formation used to look like.

12. THERE’S EVEN AN OLD MAN OF THE MOUNTAIN FLOWER.

Old-Man-of-the-Mountain, or tetraneuris grandiflora, is found in the Intermountain Regions and Rocky Mountains in states like Wyoming, Montana, Utah, Colorado, and Idaho. It’s sometimes called an alpine sunflower and got its common name from the wooly hairs that cover its leaves.

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Stones, Bones, and Wrecks
Take a Closer Look at the $17 Billion 'Holy Grail of Shipwrecks'

Feast your eyes on these new images of the treasure among the wreckage of the Spanish ship San José, often called the "holy grail of shipwrecks." When it sank on June 8, 1708, it was carrying gold, silver, jewels, and other precious cargo worth roughly $17 billion today. Now, Woods Hole Oceanographic Institution (WHOI) is revealing the major role it played in the 2015 expedition to find the San José.

The three-masted, 62-gun Spanish galleon exploded and sank at the hands of the British during the War of the Spanish Succession. It was carrying its riches to the Colombian city of Cartegena to finance the war. Archaeologists had been trying to find the San José for decades before it was finally located on November 27, 2015, during an expedition organized by Colombia, Maritime Archaeology Consultants (MAC), and WHOI. The multibillion-dollar treasure, which still sits nearly 2000 feet below the surface of the ocean near Cartegena, is just now being revealed.

WHOI's autonomous underwater vehicle REMUS 6000 was responsible for finding the elusive wreck. REMUS has been with the project since the beginning: The machine created the first side-scan sonar images of the site. After that, REMUS journeyed to a point 30 feet above the site and captured high-resolution photos of the ship's distinctive bronze cannons, which are engraved with dolphins. REMUS's documentation of this defining feature allowed scientists to positively identify the wreck as the fabled San José. (Thanks to whoever had the idea to put dolphins on the cannon in the first place.)

WHOI also released REMUS's photos of the wreckage, which show details of the horde, including ceramics and those famous cannons. "This constitutes one of the greatest—if not the biggest, as some say—discoveries of submerged patrimony in the history of mankind,” Colombian president Juan Manuel Santos said back when the treasure was discovered.

The San José's treasure is the subject of a legal battle for ownership between Colombia and U.S. salvage company Sea Search Armada, which helped look for the wreck. In 2011, four years before the San José was even found, the court ruled that the booty belongs to Colombia, but the dispute is ongoing. Because of the legal drama, the exact location of the wreck remains a government secret.

Below, check out the newly released pictures for a closer look at cannons, teacups, and other ceramics.

cannons from the San Jose
Woods Hole Oceanographic Institution

pots from the San Jose
Woods Hole Oceanographic Institution

teacups from the San Jose
Woods Hole Oceanographic Institution

REMUS 6000
REMUS 6000
Mike Purcell, Woods Hole Oceanographic Institution


A mosaic of images taken by the REMUS 6000 depicts the whole site.
A mosaic of images taken by the REMUS 6000 depicts the whole site.
Jeff Kaeli, Woods Hole Oceanographic Institution

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