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How the Black Death reached Europe – new research on the pandemic’s spread

“When, how, and why did the Black Death reach Europe?” These are the questions asked by Hannah Barker. In a new article, the historian finds that the long-believed story of how this great medieval plague reached Europe is likely untrue, and that the story of the pandemic’s spread has to deal with grain and trade.

Barker, an assistant professor of history at Arizona State University, has published her research in the latest issue of Speculum. She examined various records related to the Black Sea when the Black Death reached this region. It is from here that it spread to Italy in late 1347 / early 1348.


Countless books of history have commented about the arrival of the Black Death in Europe, explaining that the pandemic had first spread to the Black Sea region, which was governed by the Mongol-ruled state known as the Golden Horde. They are largely based on an account written by an Italian notary named Gabriele de’ Mussi. His work, Historia de morbo, was composed in 1348 or early 1349, and lays the blame on the plague’s spread to the Mongols, who he calls Tatars. It stems from a siege of a Genoese controlled port of Caffa, which is located on the coast of Crimea and is now called Feodosia.

According to Mussi, the Mongols had been laying siege to the port for three years when the plague struck their camp in 1346. He goes on to explain:


The dying Tartars, stunned and stupefied by the immensity of the disaster brought about by the disease, and realizing that they had no hope of escape, lost interest in the siege. But they ordered corpses to be placed in catapults and lobbed into the city in the hope that the intolerable stench would kill everyone inside. What seemed like mountains of dead were thrown into the city, and the Christians could not hide or flee or escape from them, although they dumped as many of the bodies as they could in the sea. And soon the rotting corpses tainted the air and poisoned the water supply, and the stench was so overwhelming that hardly one in several thousand was in a position to flee the remains of the Tartar army. Moreover one infected man could carry the poison to others, and infect people and places with the disease by look alone. No one knew, or could discover, a means of defense.

Sailors and merchants fled from Caffa, but they brought the disease with them, including to Venice and Genoa, and the pandemic spread so that as Mussi tells it, “every city, every settlement, every place was poisoned by the contagious pestilence, and their inhabitants, both men and women, died suddenly.”

While the account looks compelling, there are some problems and questions it raises. First, during this entire period, Gabriele de’ Mussi was living and working in the Italian city of Piacenza, far from the Black Sea and with no direct knowledge of what was happening at Caffa. Secondly, if the plague reached Caffa in 1346, why does it take 12 to 18 months before it comes to Europe?

In this new article Barker examines more direct evidence of what was happening in the Black Sea region during the 1340s: “Byzantine, Genoese, Venetian, and Mamluk residents and travelers in the Black Sea region wrote letters, diplomatic reports, legal documents, chronicles, and memoirs that have survived. These sources are not new discoveries; they have simply never been used to tell the story of the Black Death before.”


The sources reveal many new interesting facts, including that Caffa was besieged twice, the first time in February 1344 and then again in 1346-7. It was during the first siege that Mongols made use of twelve trebuchets, but their attack quickly ended. Meanwhile, there is no evidence that siege weapons were used in the latter attempt. It seems that in Gabriele de’ Mussi’s account, he combined both sieges into one event. Other sources, including a letter from the residents of Caffa to Genoa, indicate that the plague did not strike the city until after the second siege was lifted.

If Caffa was not the source of the plague transmission to Europe, then where did it come from? Barker offers a new answer, that it spread from another Black Sea port called Tana. Like Caffa, this port was extensively used by Genoese and Venetian merchants, where they would buy up a wide variety of trade goods such as silk, spices, and most importantly grain. Cities such as Genoa and Venice needed large quantities of grain to feed their residents, and by the fourteenth century were importing it from outside of Italy. The region around the Black Sea was a large exporter of grain to these cities, with as much as one-third of their supply coming from this area.

Portolan chart of the Black Sea, by Guillem Soler, circa 1380.

However, when the Black Death reached Tana in 1346, it did not initially spread to Italian merchants. This was because the Venetians and Genoese had imposed trade embargoes against the Golden Horde and its ports in retaliation for their attacks against Caffa. The Golden Horde also instituted their own embargoes against the Italians as well, and so trade was effectively cut off for 1346. These actions are the reason why the plague did not come to Europe that year.


It would not be until 1347 that trade again would open up between the Italian merchants and the Black Sea ports. It did not come too soon, as the Italian cities were facing food shortages, and fleets were sent to Tana with orders only to buy only grain. Once the harvest was ready in July or August of 1347, the grain was stored at Tana, and then picked up by Venetian and Genoese ships. The ships would also pick up the rats that were living in these storage areas, along with the fleas that harbored the Yersinia pestis bacteria.

It would take over a couple of months before the Venetians and Genoese ships would return back to their home ports. Barker also finds the plague started to spread differently even before they reached Italy, with the disease spreading human-to-human among the Genoese crew as they entered the Mediterranean. As they stopped in places like Sicily and Naples, these crews spread it to other populations. One chronicler in Messina explains that when twelve Genoese galleys reached this port in October 1347, they were spreading the Black Death very quickly:

if anyone so much as spoke with one of [the Genoese] he was infected with the deadly illness and could not avoid death . . . breath spread the infection among those speaking together, with one infecting the other, and it seemed as if the victim was struck all at once by the affliction.

Rumours of the plague soon spread along the Italian coast, but the fleets carried on and arrived in Genoa in November, with the city soon feeling the effects of the pandemic. Meanwhile, the Venetian ships had also returned home, but the plague would not hit the city until late February or early March. Barker believes that it took later to be hit because it was still only being transmitted animal-to-human for several weeks afterward.


Barker ultimately concludes that the siege of Caffa and the story of infected bodies being hurled into the city was not the event that brought the Black Death to Europe. She writes. “it was only when peace was restored, the embargoes were lifted, and shipment of the 1347 grain harvest began that the Black Death crossed the Black Sea and entered the Mediterranean. Plague’s movement across the Black Sea was certainly not a matter of bioterrorism during the siege of Caffa. Instead, it was an unintended consequence of peace.”

The article, “Laying the Corpses to Rest: Grain, Embargoes, and Yersinia pestis in the Black Sea, 1346–48,” by Hannah Barker, appears in the January 2021 issue of Speculum. You can access it from the University of Chicago Press website.

Hannah Barker is also the author of the award-winning book That Most Precious Merchandise: The Mediterranean Trade in Black Sea Slaves, 1260-1500, which was released in 2020. You can find out more information about Barker’s research on her university web page.

See also: Defending Venice against the Black Death

See also: The Black Death and COVID-19 with Winston Black