The collapse and breakup of the Mongol Empire in the 1260s is usually thoroughly explained
through the political tumult following the death of Great Khan Mongke in 1259.
Dying while campaigning in China’s Sichuan province, Mongke’s death provided an opportunity
for his brothers Kublai and Ariq Boke to fight for the throne, launching a series of civil
wars which permanently ended Mongol unity.
But what if we told you that Mongke’s death was not the mere accidental result of a stray
crossbow bolt, but an unforeseen consequence of a volcanic eruption that affected the whole
of Eurasia?
Today, we will explain a brand-new theory and highlight a little-known volcanic eruption
of the mid-13th century, offering another insight on how climate and environment intertwine
with human history- and how it played a role in the collapse of history’s largest contiguous
land empire.
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For decades, historians have not shied away from investigating the role climate and environment
played on the Mongol Empire.
A well-known article by Neil Pederson et al., utilized tree ring data to demonstrate that
a prolonged drought in late twelfth century Mongolia was followed by an exceptionally
warm and wet period in the early thirteenth century.
A dry and cold late twelfth century, stressing resources and starving animals, likely contributed
to the constant fighting which saw the warlord Temujin eventually overcome his rivals.
After uniting Mongolia in 1206 and taking the title of Chinggis Khan, a 15-year period
between 1211 and 1225 of consistently warm and wet weather in Mongolia unlike any other
in the last 1000 years followed.
To the newly unified tribes, it seemed Heaven expressed its support for Chinggis Khan by
providing perfect conditions for more productive grassland, a boon to the Mongols’ herds
which in turn supported the early conquests.
Other studies, such as a well-known article by Ulf Büntgen and Nicola di Cosmo, have
argued that wet conditions in Hungary in early 1242 forced the Mongol withdrawal there, though
it has not found widespread acceptance among scholars.
But climate has always taken a back seat when it comes to discussing the breakup of the
Mongol Empire into independent Khanates in the 1260s.
Mongke Khan’s death while campaigning against Song Dynasty fortresses in Sichuan prompted
a race to the throne by his brothers, sparking a conflict which permanently ended Chinggisid
unity.
For most scholars, this explanation has been perfectly sufficient.
Yet a new theory offered by Zsolt Pinke, Stephen Pow, and Zoltan Kern offers an entirely overlooked
contributing factor, which was exacerbated by these political developments.
For this, we must leave the Sichuan basin and look to the island of Lombok of modern
Indonesia.
On Lombok, likely in late 1257, the volcano of Samalas underwent a massive eruption, leaving
only an 8-kilometre-wide caldera behind.
Learned about only comparatively recently by the scientific community, the eruption
was one of the largest of the last 10,000 years and ranks a magnitude 7 on the Volcanic
Explosivity index- in comparison, the famous eruptions of Vesuvius and Mt. St. Helens registered
as a 5.
No other volcano sent as much volcanic sulphur into the stratosphere within the last 7,000
years, an amount greater than even the more famous eruptions of Tambora (1815) or Krakatoa
(1883).
Though sometime in late 1257 remains the most commonly cited date, arguments for earlier
in the 1250s have also been put forward by scholars like Martin Bauch.
Massive volcanic eruptions can have dramatic effects on the global climate, particularly
for volcanoes close to the equator, such as Lombok.
By spreading sulphur rich gases throughout the atmosphere, the eruption reduced incoming
solar radiation, which in turn reduced the global surface temperature.
The result was intense and unusual weather recorded around the world.
First, on the island of Lombok itself comes the Babad Lombok, written on palm leaves in
Old Javanese, which records the eruption of Samalas; the catastrophic eruption tore down
the volcano, wiping away the capital city of Pamatan and forcing evacuations of numerous
villages and untold deaths.
In Japan, unusually wet years and possible volcanic dust veils followed, causing widespread
crop failures culminating in the Shōga famine, causing civil discontent and banditry.
In Korea, crop failures compounded the disaster from the prolonged conflict with the Mongols;
the long resisting military government finally collapsed in 1258 as starvation undermined
what little remained of its support.
In China, 1258 was recorded as exceptionally dry, causing crop failures and famine.
The Song Emperor issued several edicts to Heaven for rain- and when it finally came
in 1259, it came in intense amounts that caused flooding and spread disease.
In the Rus’ principalities, frost was reported until the start of the summer in 1259, and
famine affected both farmers and their livestock.
In the Caucasus, extreme cold and starvation were there too recorded, as well as summer
snowfalls.
Considerable charter and chronicle material supported by tree ring data, builds an image
of widespread ecological issues across Europe.
It seems already over the 1250s food issues and poor harvests had been consistent, but
the eruption aggravated an ongoing crisis; descriptions of famine, epidemic, and flooding
spike dramatically in 1258.
The winter of 1257-8 was exceptionally wet and cold.
In France, the spring of 1258 was excessively cold and resulted in bread, meat and wine
shortages.
England too reported uninterrupted heavy rain over the winter, and the city of London was
forced to import grain from Germany.
In the Holy Roman Empire, the rains led to flooding which washed away bridges and villages.
In northern Italy, the most detailed data is recorded in the sufferings of individual
cities.
Riots over the multi-year long crisis in Perugia sparked the well-known flagellant movement
in 1259.
Sweeping across Europe, people punished themselves to seek God’s forgiveness for the crisis.
With disasters reported along the fringes of the Eurasian continent, it begs the question;
what was the effect on the area between them?
At that time, almost all of this area was under the rule of the Mongol Empire.
Only three years after the eruption of Samalas, this same empire broke into independent Khanates.
But possible mentions of ecological disaster have been previously overlooked; the new,
massive rounds of imperial expansion in the late 1250s and ensuing civil wars proved a
great distraction to the contemporary authors within the empire.
Food shortages can be as easily ascribed to thousands of Mongols and their horses trampling
over farmland, as they can sudden weather shifts.
But here is where Pow, Pinke and Kern make their contribution to the scholarship, by
identifying conditions worsened by the eruption, which affected Mongke’s fate and the course
of the fighting in the Toluid Civil war.
In 1258, Great Khan Mongke launched a massive, multipronged assault on the Song Dynasty.
Mongke personally led the force into Sichuan, where after initial success found his advance
ground to a halt at the fortress of Diaoyucheng.
Here, 20 days of heavy rainfall made military operations untenable, howling winds throwing
siege ladders to the ground.
Frustration set in as a disease outbreak spread amongst Mongke’s troops.
The heavy rainfall and immobile troops left little access to clean water.
Mongke is specifically described in Chinese and Persian sources as drinking wine to avoid
taking in any contaminated water.
The situation grew tense, one of Mongke’s lead generals, a Chinese man named Wang Decheng,
was killed in an assault on the fortress.
Finally, on the 11th of August 1259, Mongke himself succumbed, either to the disease spreading
among the troops or, in some later Chinese accounts, by a projectile lobbed by the defenders.
With Mongke’s death, his brothers Kublai and Ariq Boke both attempted to claim the
vacant throne themselves, leading to the civil war which ended Mongol imperial unity.
Now you may be wondering, where does the volcano fit into this?
The continuous rainfall seems an obvious answer, but heavy rain in the Sichuan basin in the
summer is not unusual.
No, rather the culprit is more microscopic- the disease which claimed Mongke, very likely
cholera.
To explain this rather unusual relationship, we need to use some more modern examples.
The Tambora [Indonesia] eruption of 1815, the Cosigüina[Nicaragua] eruption of 1835
and the Pinatubo [Philippines] eruption of 1991 all preceded cholera outbreaks in Bengal,
in 1817 [“First Cholera Pandemic,”], 1837, and 1992.
Pinke, Pow and Kern have identified these eruptions as possibly ideal conditions for
a cholera outbreak.
As described earlier, eruptions eject large amounts of sulfur rich gases and particulates
into earth’s atmosphere, reducing incoming solar radiation and reducing the global mean
temperature.
Researchers like Dätwyler et al., have demonstrated that such events can affect the planet’s
dominant means of climate variability over the tropical pacific, the El Niño-Southern
Oscillation, or ENSO.
Essentially, it creates the likelihood for a stronger El Niño event, raising the surface
temperature of the ocean, especially in the Bay of Bengal, and disturbing the Asian monsoon
season.
It is the opinion of Pinke, Pow and Kern that Samalas in 1257 did just this, which through
affecting the monsoons would have accounted for droughts experienced in 1258, followed
by excessive rainfall in 1259.
Through this El Niño event, they hypothesize, the warming waters in the Bay of Bengal become
ideal conditions for a phytoplankton and zooplankton bloom.
And carried among these copepods are various strands of v. cholerae, the organism which
causes cholera in humans.
The theory goes that this plankton bloom in the Bay of Bengal, upon reaching the densely
populated Ganges Delta, caused an above average incidence of cholera in the local population,
as seen in the 1817 epidemic.
Contemporary Indian sources do not describe a pandemic at this time, but sources from
the Delhi Sultanate only tend to mention diseases if they affected the ruler or princes.
The theory by Pinke, Pow and Kern suggests that this emerging epidemic spread from Bengal
through the trade routes into Yunnan, where Mongol armies were preparing to strike out
at the Song Dynasty.
The 1817 pandemic, for instance, reached China quicker through these southeast Asian overland
routes faster than it came to China’s port cities by sea.
Both Yuan and Song dynasty sources refer to a significant epidemic striking China over
1259 and 60; early in 1259, Mongke even held a quriltai to decide on whether they should
progress into these conditions.
Mongke decided on campaigning anyways, only for his army to become stuck in mud and sieges
in Sichuan, where this epidemic spread among his men.
It seems Uriyangqadai’s army, operating in southern China, and Kublai’s army, besieging
what is now modern-day Wuhan, all suffered a bout of this disease, though the evidence
is less clear.
While the popular image persists of medieval peoples not understanding how disease spread,
both Chinese and Persian sources have Mongke drink wine in order to avoid the water, evidently
noting how men forced to drink the tainted water grew violently ill and died.
However, Mongke’s efforts were in vain, and as described in the history of Rashid
al-Din, he caught the illness spreading among the men.
The description given by Rashid al-Din matches the symptoms of cholera.
For the later Chinese accounts of Mongke being killed by a projectile from the defenders,
it is likely this was a conflation with the fate of Mongke’s commander Wang Dechang,
who was killed by them.
Remembering that they killed a prominent commander, and remembering that the Khan died soon after,
it is not a far distance for the two events to become merged into one in later local memory.
“When summer came and the heat rose, bloody diarrhea from the water and air of the region
broke out, and a vabā fell on the Mongol army, so that many of them died.
The padishāh of the world, in order to guard himself from the vabā, drank wine, and was
constant in this practice.
Suddenly he got abdominal pains, and the disease degenerated into a crisis.”
-Rashid al-Din, translated by Simon Berger.
Mongke’s death, likely of cholera, was an indirect consequence of the eruption of Samalas,
and it had immense consequences on the Mongol Empire.
With no designated successor, two of his brothers, Kublai and Ariq Boke, now raced for the open
throne.
Ariq based himself at the imperial capital of Karakorum in Mongolia, while Kublai situated
himself in north China.
Wielding the resources of northern China, Kublai of course had a significant advantage,
and indeed denied Ariq access to valuable grain shipments to feed Karakorum.
Furthermore, primary sources like Rashid al-Din supported by tree ring data, describe a drought
and harsh winter plaguing Ariq’s forces: from Mongolia, the Yenisei River valley to
Almaliq, hunger stalked the steppes in the early 1260s.
Ariq’s men and horses withered and died, his followers abandoning him until he surrendered
to Kublai in 1264.
Samalas’ impact on the Eurasian weather patterns may have induced severe drought upon
Mongolia, and when coupled with Kublaii denying Ariq Boke access to Chinese resources, ensured
starvation among Ariq’s followers and herds, ensuring Kublai’s eventual victory as Khan.
By the time of Ariq’s surrender, Kublai was now Khan of only a quarter of the empire,
his war with Ariq providing time for their cousins in the west to carve out their own
empires.
The Samalas eruption did not directly annihilate the Mongol Empire; rather, it affected climatic
conditions around the world which compounded tensions long building within the Mongol Empire.
The volcano’s impact on the Asian climate simply opened a window for these tensions
to bubble violently to the surface.
Samalas may have influenced weather systems which resulted in droughts, heavy rainfalls
or ideal scenarios for the spread of cholera, but Samalas was not responsible for Mongke’s
choice to not appoint a successor, nor his decision to attack the Song Dynasty.
It provided conditions beneficial for Kublai to stake his claim for the Khanate, but Samalas
did not make him go to war with his brother.
Such is the relationship between humanity and climate; climate and environment may encourage
human decisions or stress societal relationships, but it is still upon humans to act on it.
In the case of the Mongol Empire, the Samalas eruption may have indirectly influenced the
specific method of its dissolution in 1260.
Such is the argument provided by these researchers.
We will continue to explore Mongol history in future videos, so make sure you’ve subscribed
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