The Silk Road, a network of land and sea trade routes that linked China and the Far East to Europe from 130 BC. in 1453 AD, became a vital source for everything from fabrics and leather goods to spices and precious stones. It connected communities and allowed them to share innovations such as paper making and printing technology, as well as language, culture and religious beliefs.
But the medieval superhighway also has a darker and deadly legacy: it allowed one of the first great pandemics - the plague known as the black plague - to spread along its route and ultimately reach the edge of Europe, where it killed more than 50 million people. Between 1346 and 1352.
"The Silk Road allowed, perhaps for the first time, the sustained transmission of diseases endemic to Central Asia to move along the Europe Route", explains Mark Welford, professor at the University of Northern Iowa and author of the 2018 book Geographies of plague pandemics.
READ MORE: The Black Death: Chronology of the Terrible PandemicThe Silk Road becomes a network of infection
Imagno / Getty Images
As Welford explains, one of the reasons the Silk Road has been so effective in helping the spread of pathogens is that, despite its name, it was not just one road. The land part of the Silk Road was actually a set of paths that separated and reconnected across the steppes of Central Asia, almost like the blood vessels of the human body or the veins of the leaves of plants.
Along this network there were various stops - villages, towns and outposts called cavaranserais - scattered about a day's walk from each other. Few travelers have traveled the length of the Silk Road, which stretches thousands of miles from East Asia to Turkey. Instead, caravans of traders and camels traveled between local nodes, exchanging their goods for other goods, gold or silver, and then returned home. (Here is a map of the basic route, from The Miami University Silk Road project.)
In the process, traders and their animals also transmitted contagions, which spread slowly and gradually between the points of the Silk Road. Unfortunately, the route has also brought travelers close to what some researchers refer to as a source of a particularly dangerous disease.
Contagious fleas leave rodent hosts for humans
VCG Wilson / Corbis / Getty Images
In a 2015 study, Norwegian and Swedish scientists proposed that fluctuations in the climate of the Central Asian steppes are causing the region's rodent population to collapse - probably gerbils and marmots in particular. This, in turn, may have forced fleas that carried the bacteria Yersinia pestis, which causes the plague,to leave their rodent hosts and find new places to live, such as camels and their human owners. After several years of relocation of fleas, according to scientists' theory, it took the caravans another decade to progressively move the plague westwards, until it reached the edge of Europe.
Kaffa, a Black Sea port of Crimea now known as Feodosia, "appears to be the starting point for the primary wave of medieval black plague from Asia in Europe in 1346-1377," says Welford. "The Genoese or the Venetians left Kaffa by boat, infected Constantinople and Athens as they were heading for Sicily, Venice and Genoa. But I suspect [Black Death] also reached Constantinople by land. "
A famous story from the 14th century claimed that the plague was deliberately introduced into Kaffa, during a Mongolian biological warfare attack that involved throwing plague-infected corpses onto the city walls.
Black plague spreads east to west, then back
WATCH: How the Black Death has spread so widelyWhether this really happened, the plague finally became a disaster in the East as in the West. "It has killed many Mongolian leaders and other elites, and weakened the military and local economies," said Christopher I. Beckwith, a prominent professor at Indiana Bloomington University and author of the 2011 book. Silk Road Empires. Black plague is estimated to have killed 25 million people in Asia and North Africa between 1347 and 1350, in addition to the carnage in Europe.
A 2019 study by German researchers genetically linked the Black Death to an epidemic that occurred in 1346 in Laishevo in the Volga region of Russia, raising the possibility that the disease had spread from Asia in several ways.
In any case, when the black plague reached Europe, it attacked an already weakened population and malnourished by the brutal nature of the feudal economy.
"I think it can be argued that [Black Death] struck at a time when the health of the poor was compromised by the stress of famine, poverty and the very nature of serfdom, "says Welford.
Between March and July of this horrible year, Boccaccio noted that more than 100,000 residents of the city died, their bodies piled up outside the doors. The grand palaces and stately homes where the nobility and their servants had lived were left empty, so that the city was "almost depopulated".
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The newly connected world is forced to quarantine
Without modern scientific knowledge and antibiotics, Europeans have struggled through trial and error to find ways to combat the anger of the bacteria. "The decline in plague has occurred due to the combined use of quarantine, lazarettes, plague hospitals and the rudimentary use of masks by doctors, the establishment of health cords and closing borders, and using health spies to warn countries of the impending plague, "says Welford.
But the black plague was not completely over. Different strains of the same bacteria returned to ravage Europe over and over again until the 1700s. Science According to a magazine published in 2016, researchers have discovered that a strain of the disease that developed in Europe eventually headed east and killed millions of people in China in the 1800s.
The spread of the black plague coincided with the start of a smaller, more connected and integrated world, thanks in part to the Silk Road. Along its routes, microbes spread as easily as people, inventions and ideas.
See all pandemic coverage here.