The Black Death, also known as the Pestilence, Great Bubonic Plague, the Great Plague or the Plague, or less commonly the Black Plague or the Great Mortality, was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people in Eurasia, peaking in Europe from 1347 to 1351.

The bacterium Yersinia pestis, which results in several forms of plague (septicemic, pneumonic and, the most common, bubonic), is believed to have been the cause.

The Black Death was the first major European outbreak of the plague and the second plague pandemic.

The Black Death created a number of religious, social and economic upheavals, with profound effects on the course of European history.

The Black Death probably originated in Central Asia or East Asia, from where it traveled along the Silk Road, reaching Crimea by 1343.

From there, it was most likely carried by fleas living on the black rats that traveled on Genoese merchant ships, spreading throughout the Mediterranean Basin, reaching the rest of Europe via the Italian peninsula.

The Black Death is estimated to have killed 30% to 60% of Europe’s population. In total, the plague may have reduced the world population from an estimated 475 million to 350–375 million in the 14th century.

It took 200 years for Europe’s population to recover to its previous level and some regions like Florence only recovered by the 19th century. The plague recurred as outbreaks until the early 20th century.


The plague disease, caused by Yersinia pestis, is enzootic (commonly present) in populations of fleas carried by ground rodents, including marmots, in various areas, including Central Asia, Kurdistan, Western Asia, North India, and Uganda.

Due to climate change in Asia, rodents began to flee the dried-out grasslands to more populated areas, spreading the disease. Nestorian graves dating to 1338–1339 near Issyk-Kul in Kyrgyzstan have inscriptions referring to plague, and are thought by many epidemiologists to mark the outbreak of the epidemic, from which it could easily have spread to China and India.

In October 2010, medical geneticists suggested that all three of the great waves of the plague originated in China. However, research in 2018 found evidence of Yersinia pestis in an ancient Swedish tomb, which may have been the cause of what has been described as the Neolithic decline around 3000 BCE, in which European populations declined significantly. This would suggest the pathogen originated in Europe, rather than Asia.

The 13th-century Mongol conquest of China caused a decline in farming and trading. Economic recovery had been observed at the beginning of the fourteenth century. In the 1330s, many natural disasters and plagues led to widespread famine, starting in 1331, with a deadly plague arriving soon after.

Epidemics, that may have included the plague, killed an estimated 25 million across Asia during the fifteen years before it reached Constantinople in 1347.

The disease may have traveled along the Silk Road with Mongol armies and traders, or it could have arrived via ship. By the end of 1346, reports of plague had reached the seaports of Europe:

“India was depopulated, Tartary, Mesopotamia, Syria, Armenia were covered with dead bodies”.

The plague was reportedly first introduced to Europe via Genoese traders from the port city of Kaffa in the Crimea in 1347. During a protracted siege of the city by the Mongol army under Jani Beg, whose army was suffering from the disease, the army catapulted infected corpses over the city walls of Kaffa to infect the inhabitants.

The Genoese traders fled, taking the plague by ship into Sicily, then the Italian mainland, whence it spread north. Whether or not this hypothesis is accurate, it is clear that several existing conditions, such as war, famine, and weather, contributed to the severity of the Black Death.

Among many other culprits of plague contagiousness, malnutrition, even if distantly, also contributed to such an immense loss in the European population, since it weakened immune systems.

European outbreak

There appear to have been several introductions into Europe. The plague reached Sicily in October 1347, carried by twelve Genoese galleys, and rapidly spread all over the island.

Galleys from Kaffa reached Genoa and Venice in January 1348, but it was the outbreak in Pisa a few weeks later that was the entry point to northern Italy. Towards the end of January, one of the galleys expelled from Italy arrived in Marseille.

From Italy, the disease spread northwest across Europe, striking France, Spain (which was hit due to the heat – the epidemic raged in the early weeks of July), Portugal and England by June 1348, then spread east and north through Germany, Scotland and Scandinavia from 1348 to 1350.

It was introduced into Norway in 1349 when a ship landed at Askøy, then spread to Bjørgvin (modern Bergen) and Iceland. Finally, it spread to northwestern Russia in 1351. The plague was somewhat more uncommon in parts of Europe with less developed trade with their neighbors, including the majority of the Basque Country, isolated parts of Belgium and the Netherlands, and isolated alpine villages throughout the continent.

According to some epidemiologists, periods of unfavorable weather decimated plague-infected rodent populations and forced their fleas onto alternative hosts, inducing plague outbreaks which often peaked in the hot summers of the Mediterranean, as well as during the cool autumn months of the southern Baltic states.

However, other researchers do not think that the plague ever became endemic in Europe or its rat population. The disease repeatedly wiped out the rodent carriers, so that the fleas died out until a new outbreak from Central Asia repeated the process.

The outbreaks have been shown to occur roughly 15 years after a warmer and wetter period in areas where plague is endemic in other species, such as gerbils.

Middle Eastern outbreak

The plague struck various regions in the Middle East during the pandemic, leading to serious depopulation and permanent change in both economic and social structures.

It may have spread from Central Asia with the Mongols to a trading post in Crimea, called Kaffa, controlled by the Republic of Genoa. As infected rodents infected new rodents, the disease spread across the region, including South Africa entering also from southern Russia.

By autumn 1347, the plague reached Alexandria in Egypt, through the port’s trade with Constantinople, and ports on the Black Sea. During 1347, the disease traveled eastward to Gaza, and north along the eastern coast to cities in modern Lebanon, Syria, Israel, and Palestine, including Ashkelon, Acre, Jerusalem, Sidon, Damascus, Homs, and Aleppo.

Within two years, the plague had spread throughout the entire Muslim empire from Arabia across North Africa. In 1348–1349, the disease reached Antioch. The city’s residents fled to the north, but most of them ended up dying during the journey.

Mecca became infected in 1349. During the same year, records show the city of Mawsil (Mosul) suffered a massive epidemic, and the city of Baghdad experienced a second round of the disease.

Muslim religious scholars taught that the plague was a “martyrdom and mercy” from God, assuring the believer’s place in paradise. For non-believers, it was a punishment.

Some Muslim doctors cautioned against trying to prevent or treat a disease sent by God. Others adopted many of the same preventive measures and treatments for the plague used by the Europeans. These Muslim doctors also depended on the writings of the ancient Greeks.

Alternative explanations

The plague theory implicating Y. pestis was first significantly challenged by the work of British bacteriologist J. F. D. Shrewsbury in 1970, who noted that the reported rates of mortality in rural areas during the 14th-century pandemic were inconsistent with the modern bubonic plague, leading him to conclude that contemporary accounts were exaggerations.

In 1984, zoologist Graham Twigg produced the first major work to challenge the bubonic plague theory directly, and his doubts about the identity of the Black Death have been taken up by a number of authors, including Samuel K. Cohn, Jr. (2002 and 2013), David Herlihy (1997), and Susan Scott and Christopher Duncan (2001).

It is recognized that an epidemiological account of the plague is as important as an identification of symptoms, but researchers are hampered by the lack of reliable statistics from this period.

Most work has been done on the spread of the plague in England, and even estimates of the overall population at the start vary by over 100% as no census was undertaken between the time of publication of the Domesday Book and poll tax of the year 1377. Estimates of plague victims are usually extrapolated from figures for the clergy.

In addition to arguing that the rat population was insufficient to account for a bubonic plague pandemic, skeptics of the bubonic plague theory point out that the symptoms of the Black Death are not unique (and arguably in some accounts may differ from the bubonic plague); that transference via fleas in goods was likely to be of marginal significance; and that the DNA results may be flawed and might not have been repeated elsewhere or were not replicable at all, despite extensive samples from other mass graves.

Other arguments include the lack of accounts of the death of rats before outbreaks of plague between the 14th and 17th centuries; temperatures that are too cold in northern Europe for the survival of fleas; that, despite primitive transport systems, the spread of the Black Death was much faster than that of modern bubonic plague; that mortality rates of the Black Death appear to be very high; that, while the modern bubonic plague is largely endemic as a rural disease, the Black Death indiscriminately struck urban and rural areas; and that the pattern of the Black Death, with major outbreaks in the same areas separated by 5 to 15 years, differs from modern bubonic plague&npsp;– which often becomes endemic for decades with annual flare-ups.

McCormick has suggested that earlier archaeologists were simply not interested in the “laborious” processes needed to discover rat remains. Walløe complains that all of these authors “take it for granted that Simond’s infection model, black rat → rat flea → human, which was developed to explain the spread of plague in India, is the only way an epidemic of Yersinia pestis infection could spread“, whilst pointing to several other possibilities.

Similarly, Green has argued that greater attention is needed to the range of (especially non-commensal) animals that might be involved in the transmission of plague.

A variety of alternatives to Y. pestis have been put forward. Twigg suggested that the cause was a form of anthrax, and Norman Cantor thought it may have been a combination of anthrax and other pandemics. Scott and Duncan have argued that the pandemic was a form of infectious disease that they characterize as hemorrhagic plague similar to Ebola.

Archaeologist Barney Sloane has argued that there is insufficient evidence of the extinction of numerous rats in the archaeological record of the medieval waterfront in London and that the plague spread too quickly to support the thesis that Y. pestis was spread from fleas on rats; he argues that transmission must have been person to person.

This theory is supported by research in 2018 which suggested transmission was more likely by body lice and human fleas during the second plague pandemic.

However, no single alternative solution has achieved widespread acceptance. Many scholars arguing for Y. pestis as the major agent of the pandemic suggest that its extent and symptoms can be explained by a combination of bubonic plague with other diseases, including typhus, smallpox, and respiratory infections.

In addition to the bubonic infection, others point to additional septicemic (a type of “blood poisoning”) and pneumonic (an airborne plague that attacks the lungs before the rest of the body) forms of the plague, which lengthen the duration of outbreaks throughout the seasons and help account for its high mortality rate and additional recorded symptoms.

In 2014, Public Health England announced the results of an examination of 25 bodies exhumed in the Clerkenwell area of London, as well as of wills registered in London during the period, which supported the pneumonic hypothesis.

The historian George Hussman claimed that the plague had not occurred in East Africa until the 1900s. However, other sources suggest that the Second pandemic did indeed reach Sub-Saharan Africa.


Death toll

There are no exact figures for the death toll; the rate varied widely by locality. In urban centers, the greater the population before the outbreak, the longer the duration of the period of abnormal mortality. It killed some 75 to 200 million people in Eurasia. According to medieval historian Philip Daileader in 2007:

The trend of recent research is pointing to a figure more like 45–50% of the European population dying during a four-year period. There is a fair amount of geographic variation. In Mediterranean Europe, areas such as Italy, the south of France and Spain, where plague ran for about four years consecutively, it was probably closer to 75–80% of the population. In Germany and England … it was probably closer to 20%.

A death rate as high as 60% in Europe has been suggested by Norwegian historian Ole Benedictow:

Detailed study of the mortality data available points to two conspicuous features in relation to the mortality caused by the Black Death: namely the extreme level of mortality caused by the Black Death, and the remarkable similarity or consistency of the level of mortality, from Spain in southern Europe to England in north-western Europe. The data is sufficiently widespread and numerous to make it likely that the Black Death swept away around 60 per cent of Europe’s population. It is generally assumed that the size of Europe’s population at the time was around 80 million. This implies that around 50 million people died in the Black Death.

Half of Paris’s population of 100,000 people died. In Italy, the population of Florence was reduced from 110,000–120,000 inhabitants in 1338 down to 50,000 in 1351. At least 60% of the population of Hamburg and Bremen perished, and a similar percentage of Londoners may have died from the disease as well.

In London, approximately 62,000 people died between 1346 and 1353. While contemporary reports account of mass burial pits being created in response to the large numbers of dead, recent scientific investigations of a burial pit in Central London found well-preserved individuals to be buried in isolated, evenly spaced graves, suggesting at least some pre-planning and Christian burials at this time.

Before 1350, there were about 170,000 settlements in Germany, and this was reduced by nearly 40,000 by 1450. In 1348, the plague spread so rapidly that before any physicians or government authorities had time to reflect upon its origins, about a third of the European population had already perished. In crowded cities, it was not uncommon for as much as 50% of the population to die.

The disease bypassed some areas, and the most isolated areas were less vulnerable to contagion. Monks, nuns, and priests were especially hard-hit since they cared for victims of the Black Death.

The most widely accepted estimate for the Middle East, including Iraq, Iran, and Syria, during this time, is for a death rate of about a third. The Black Death killed about 40% of Egypt’s population.


With such a large population decline from the Plague, wages soared in response to a labor shortage. Landowners were also pushed to substitute monetary rents for labor services in an effort to keep tenants.


Some historians believe the innumerable deaths brought on by the plague cooled the climate by freeing up land and triggering reforestation. This may have led to the Little Ice Age.


Renewed religious fervor and fanaticism bloomed in the wake of the Black Death. Some Europeans targeted “various groups such as Jews, friars, foreigners, beggars, pilgrims“, lepers, and Romani, blaming them for the crisis. Lepers, and others with skin diseases such as acne or psoriasis, were killed throughout Europe.

Because 14th-century healers and governments were at a loss to explain or stop the disease, Europeans turned to astrological forces, earthquakes, and the poisoning of wells by Jews as possible reasons for outbreaks. Many believed the epidemic was a punishment by God for their sins and could be relieved by winning God’s forgiveness.

There were many attacks against Jewish communities. In the Strasbourg massacre of February 1349, about 2,000 Jews were murdered. In August 1349, the Jewish communities in Mainz and Cologne were annihilated. By 1351, 60 major and 150 smaller Jewish communities had been destroyed.

jplThese massacres eventually died out in Western Europe, only to continue on in Eastern Europe. During this period many Jews relocated to Poland, where they received a warm welcome from King Casimir the Great.

*This article uses material from the Wikipedia article The Black Death, which is released under the Creative Commons Attribution-ShareAlike License 3.0 (view authors).