The Black Death
What Happened in 1346–1353, and What the Record Shows

The Black Death was a plague epidemic that swept through Europe, the Middle East and North Africa in the middle of the fourteenth century. It was the first wave of what Maria Spyrou’s team calls the second plague pandemic, which lasted nearly 500 years.

This page sets out what the sources say about what it was, where it came from, how far it spread, how many it killed and what it changed. Then it looks at nine popular claims about it, each with a verdict: Holds up, Partly, Doesn’t hold up, Still argued (when credible sources disagree) or Can’t confirm.

Where the sources give different numbers or dates, this page gives the range and says why they differ. A shorter entry on the Black Death sits in our 25 turning points in history. The story about Caffa is also covered in our Mongol Empire article.

What it was

The disease was plague, caused by the bacterium Yersinia pestis. That was argued over for a long time.

A 2010 study in PLoS Pathogens, led by Stephanie Haensch, noted that the cause of the Black Death had remained highly controversial. The team then reported DNA and protein traces of the bacterium in skeletons from mass graves in northern, central and southern Europe.

They confirmed that Y. pestis caused the Black Death and later epidemics across the whole of Europe, over four centuries.

A year later, a team led by Kirsten Bos published in Nature a rebuilt ancient genome of Yersinia pestis. It came from Black Death victims in London, securely dated to plague deaths of 1348–1350. Their analysis suggested that the Black Death was the main event that introduced and widely spread the ancestor of all plague strains that infect people today.

The World Health Organization says plague is caused by bacteria that pass from animals to people, usually found in small mammals and their fleas. Bubonic plague, marked by painful swollen lymph nodes called buboes, is the most common form.

Giovanni Boccaccio described the same swellings in Florence in 1348, in the introduction to the Decameron (J. M. Rigg’s translation, 1903). He wrote of “tumours in the groin or the armpits, some of which grew as large as a common apple, others as an egg”, which ordinary people called gavoccioli.

Where it began and how it spread

A 2022 study in Nature, led by Maria Spyrou, analysed ancient DNA from two cemeteries, Kara-Djigach and Burana, in the Chüy valley near Lake Issyk-Kul in present-day Kyrgyzstan. Their tombstones, dated 1338–1339, name pestilence as the cause of death.

The team found Y. pestis in the people buried there. They concluded that the evidence supports an early fourteenth-century source of the second plague pandemic in central Eurasia.

The paper notes that the start of the Black Death has usually been linked to outbreaks around the Black Sea in 1346. That is eight years after the epidemic at Kara-Djigach.

From there the dates run roughly like this:

• 1345: the plague was in Astrakhan, on the Caspian Sea, according to a 2020 review of the Black Death’s economics. Its authors are Remi Jedwab, Noel Johnson and Mark Koyama.
• 1346: the army of the Mongol ruler Janibeg was besieging the Genoese trading port of Caffa, in Crimea. It lifted the siege because plague devastated his forces, as Mark Wheelis of the University of California, Davis, records. He concluded that Crimea clearly played a key role as the immediate source from which the Mediterranean was infected.
• October 1347: the plague reached Messina in Sicily on Genoese ships. Both the economic review and a 2021 history of plague in The American Journal of Medicine, by Kathryn Glatter and Paul Finkelman, say so.
• 1348: it was in Florence. Boccaccio dated it to 1348 and wrote that it had begun some years before in the East. Glatter and Finkelman write that it spread to France and Spain in 1348, and then to Germany, Switzerland and Austria.
• Summer 1348: it reached England. The economic review says June 1348. The 1889 editor of the chronicler Robert of Avesbury, summarising Avesbury, has it arriving about the beginning of August 1348, first on the Dorset coast.
• 1348–1349: in Avesbury’s account, as his editor summarised it, London was struck around All Saints’ Day (1 November) and suffered until the following Whitsun.
• 1349–1350: Glatter and Finkelman write that it devastated London in 1349 and reached Scandinavia and northern England by 1350.

How long did it last? It depends on the source:

• Spyrou’s team and the 2018 study by Katharine Dean and colleagues both date the Black Death to 1346–1353.
• Haensch’s team gives 1347 to 1353.
• Bos’s team gives 1347 to 1351.
• Glatter and Finkelman give 1347 to 1352.

The start date depends on whether you count from the outbreaks around the Black Sea in 1346 or from the arrival in Sicily in October 1347. The end date depends on when each writer treats the first wave as over.

How many died

Estimates of the death toll vary widely, and the sources say so.

• The 2018 PNAS study by Dean and colleagues says the disease killed an estimated one-third of the population in Europe, the Middle East and North Africa.
• Glatter and Finkelman write that at least one third of the European population, more than 25 million people, died between 1347 and 1352.
• The WHO says it caused more than 50 million deaths in Europe.
• The economic review opens by saying it killed between 30% and 50% of the population. Later it reports that studies suggest an overall death rate of 40–60%, citing the historian Ole Benedictow.
• That review calls 40% the more conservative estimate. It says that figure fits the population-weighted average it found across 274 localities.
• Spyrou’s team writes that it is estimated to have killed up to 60% of the western Eurasian population over its eight-year course.

Why so far apart? Partly because historians’ estimates differ. In the economic review’s table of country estimates, the historian Robert Gottfried’s figure for France is 30% and Benedictow’s is 60%. For England and Scotland, Gottfried gives 45% and Benedictow 62.5%.

Partly because places differed. The same review gives 60% for Venice and Florence, 30–40% for Genoa, Prato and Pisa, and 80% for Trento against 45% for nearby Verona.

And for whole regions there is not enough to go on. The review says it is not possible to estimate deaths for Eastern Europe, the Middle East and Asia.

Writers at the time give figures too, but they are not counts. Boccaccio says that “it is believed” more than a hundred thousand people died within the walls of Florence between March and July. That is his report of what people believed, not a count.

What it changed

Wages and work

With so many workers dead, those who survived could ask for more. English law tried to stop them. The first of these laws was a royal ordinance of 1349.

The Avalon Project at Yale prints its text under the title “The Statute of Laborers; 1351”. It opens with the king’s complaint that a great part of the people, especially workmen and servants, had died in the pestilence. Some, it says, “are not willing to serve unless they receive excessive wages”.

It orders that wages stay at what was usually paid in the twentieth year of the king’s reign, that is, before the plague.

The historian Christine R. Johnson, of Washington University in St. Louis, explains that England passed first the ordinance (1349) and then the statute (1351) of labourers. Together they froze wages at pre-plague levels.

Court records show workers leaving employers and demanding more anyway. In her reading, workers pushed for higher wages and greater freedom to move, and got them.

The economic review by Jedwab, Johnson and Koyama gives a fuller picture:

• At first, things got worse. In the very short run, the plague caused a breakdown in markets and in economic activity more generally. In England, real wages for unskilled and skilled workers fell by about 20% over the next two years.
• Then wages rose. After that, wages and income per person rose. But in the long run, the rise lasted only in some parts of Europe.
• The limits worked for a while. In their reading, the English wage limits were highly effective at holding down the growth of money wages in the 1350s, but less and less effective after that. France passed a comparable statute in 1351.

Persecution of Jewish communities

By the autumn of 1348, a rumour was spreading that Jews had poisoned wells to cause the plague. Jewish prisoners were tortured until they confessed.

One such confession was taken from Agimet of Geneva at Châtel, on Lake Geneva, in October 1348. Jacob Marcus, whose 1938 sourcebook prints it in translation, calls it “typical of the confessions extorted and forwarded to other towns”.

In Strasbourg, the chronicler Jacob von Königshofen records that the Jews were burned on 14 February 1349, St Valentine’s Day. In the English of Marcus’s sourcebook, they were burned “on a wooden platform in their cemetery. There were about two thousand people of them.”

He writes that those who were willing to be baptised were spared. The burnings, he says, ran from the Mediterranean into Germany, but not in Avignon, where the pope protected them. In September 1348 Pope Clement VI had issued a bull contradicting the accusation, as Jedwab, Johnson and Koyama note.

Estimates of the scale vary with what is counted:

• Marcus wrote in 1938 that Jews were killed in at least two hundred towns and hamlets.
• Glatter and Finkelman write that at least 235 Jewish communities suffered mass persecution and destruction.
• Jedwab, Johnson and Koyama, working from city-level records, found that about half of cities with a Jewish community suffered a persecution during the Black Death.

Their study also found that cities with higher plague mortality were less likely to persecute. And for a given mortality shock, persecutions were more likely where people were readier to believe conspiracy theories that blamed the Jews for the plague. They were less likely where Jews played an important economic role.

The flagellants

Groups of lay people who whipped themselves in public spread across Europe. The practice was older than the plague. The Fitzwilliam Museum in Cambridge notes that voluntary self-flogging among lay people dates back to the middle of the thirteenth century.

After the Black Death, the museum says, flagellation was practised so widely and fervently that in 1349 Pope Clement VI condemned it. The flagellants reached England too. Avesbury’s chronicle, its editor notes, records a visit by them, a sect stirred back into action by the terror of the epidemic.

Nine popular claims, checked

1. “The Black Death was spread by rats”

Still argued Rats have long been central to the story, and the experts still disagree. The economic review repeats the usual account: the fleas (X. cheopis) of the black rat (R. rattus) are thought to be the main carriers.

A 2018 study by Katharine Dean and colleagues built models of three ways plague could spread. The model with human fleas and lice was the best fit for death records in seven of the nine outbreaks they studied. It did better than models based on rats or on infection through the air. For the other two, the outbreaks were too small to tell.

The authors present this as “ultimately challenging the assumption that plague in Europe was predominantly spread by rats”. A reply in the same journal that year, by Park and colleagues, disagreed. Its title calls spread by human ectoparasites, such as fleas and lice, “only weakly supported by proposed mathematical models”.

A 2024 laboratory study in PLoS Biology, by David Bland and colleagues, found that body lice can carry the bacterium and pass it on by biting. The authors wrote that this supports the idea that lice may have played a role in earlier human plague pandemics.

That makes the idea more plausible; it does not settle what happened in the 1340s. The question is open.

2. “The Mongols started the Black Death by throwing plague corpses into Caffa”

Doesn't hold up The Black Death did not start at Caffa, though the corpse story itself may be true. The plague was already in the besieging army.

The story of the 1346 siege of Caffa, in Crimea, comes from one account by a notary in Piacenza, Gabriele de’ Mussi. In Rosemary Horrox’s English translation (1994), the besiegers “ordered corpses to be placed in catapults and lobbed into the city”.

Wheelis reviewed the account in 2002. He found that de’ Mussi does not claim to have seen any of the events in Asia he describes. His account, Wheelis writes, is probably secondhand, with no other source to confirm it.

Wheelis thought the attack plausible, and the best explanation of how plague got into the city. But he concluded that the siege was unlikely to have played a serious part in carrying plague from the Black Sea to Europe.

Spyrou’s team traced the pandemic’s origin to central Eurasia and wrote that the exact way Y. pestis reached western Eurasia is unknown.

3. “It killed a third of Europe”

Partly A third is a real estimate, but it sits near the low end of the range. Dean’s paper gives it for Europe, the Middle East and North Africa, and Glatter and Finkelman give at least one third for Europe.

Other estimates run from 30% to 50%, from 40% to 60%, and up to 60% across western Eurasia. The WHO puts the toll at more than 50 million deaths in Europe.

The figures differ because historians’ estimates differ and because places differed. For eastern Europe, the Middle East and Asia, the economic review says, there is not enough evidence to estimate at all. The section on the death toll above gives the details.

4. “The Black Death was the first plague pandemic”

Doesn't hold up It was the first wave of the second plague pandemic. A 2019 study in PNAS, led by Marcel Keller, describes the first pandemic on record caused by Yersinia pestis. It began as the Justinianic Plague in 541, within the Roman Empire, and continued as the so-called First Pandemic until 750.

Plague in people is older still. A 2015 study in Cell, led by Simon Rasmussen, reported Y. pestis DNA in human teeth from Asia and Europe, dating from 2,800 to 5,000 years ago.

5. “‘Ring a ring o’ roses’ is about the plague”

Doesn't hold up The rhyme turns up in English centuries after the Black Death. Stephen Winick of the Library of Congress’s American Folklife Center writes that the plague reading emerged in the mid-twentieth century. It has become widespread, he says, but folklorists have never accepted it.

The rhyme doesn’t turn up in English until 1881, in Kate Greenaway’s Mother Goose. There it runs: “Ring-a-ring-a-roses, A pocket full of posies; Hush! hush! hush! hush! We’re all tumbled down.” There is no sneeze in it.

Many versions, Winick notes, have no words that sound like sneezes, and in many everyone gets up again after falling down. The first direct reference to the plague reading he found is from 1951, when the folklorists Iona and Peter Opie mentioned it and said they were not convinced.

Winick adds that several accounts of the 1665 plague year mention nothing like the rhyme.

6. “Plague doctors wore beaked masks during the Black Death”

Doesn't hold up The beaked costume belongs to the seventeenth century, long after the Black Death. The image is real; it comes from later plague years.

Marion Maria Ruisinger wrote in 2020 about the beak mask in the German Museum of the History of Medicine in Ingolstadt. She concludes that the beak mask is not mentioned before the mid-seventeenth century, and then only in Italy and southern France.

The sources disagree on the first date. The idea is credited to Charles de Lorme (1584–1678), physician to Louis XIII. The Public Domain Review says he is thought to have developed it in 1619.

Ruisinger presents that credit as reported rather than proven. She says the earliest known evidence of the mask in use relates to the epidemic in Rome in 1656. The sentence before is our translation of her words: Der früheste bekannte Beleg für die Verwendung eines solchen Nasenfutterals in Seuchenzeiten bezieht sich auf die Epidemie, die 1656 in Rom herrschte.

7. “The Black Death ended feudalism”

Partly It weakened serfdom in western Europe, but not everywhere. The claim starts from something real.

The economic review by Jedwab, Johnson and Koyama lists the end of serfdom in western Europe among the plague’s long-run effects. It says the plague weakened serfdom in western Europe, though not in eastern Europe. It also discusses why the shortage of workers led instead to a second serfdom in eastern Europe.

Johnson, the Washington University historian, writes that “scholars disagree about how and how much things changed”. She notes that they tend to describe the changes in oddly passive terms: wages rose, inequality decreased, feudalism ended. Yet, she argues, there was a great deal of deliberate action, and inaction, behind them.

In her reading, wages rose and inequality lessened, but the social and labour hierarchies stayed the same.

8. “People killed cats, and that made the plague worse”

Can't confirm We found no medieval source for a mass killing of cats before or during the Black Death.

The story is usually tied to a real papal letter: Vox in Rama, a letter of Pope Gregory IX dated 13 June 1233. We read it in the Latin edition of 1883.

A black cat (gattus niger) appears in its description of a heretics’ ritual, and the letter calls on Christians to take up the cross against the heretics. It does not order anyone to kill cats.

Whether cats would have made any difference is also unclear. The economic review notes that cats, dogs and birds might also have played a role in supporting populations of infected fleas, which points the other way.

9. “Plague no longer exists”

Doesn't hold up Plague still exists. The WHO says human plague remains endemic in several countries. From 2019 to 2025, most cases reported to the WHO were in the Democratic Republic of the Congo and Madagascar.

As an animal disease, it says, plague is found on every continent except Oceania. The WHO gives a case-fatality ratio, the share of cases who die, of 30% to 60% for the bubonic type. It says the pneumonic and septicaemic kinds are always fatal when left untreated, and that antibiotic treatment is effective against plague bacteria.

What to take from it

Three habits from this page carry over to any big story from the past:

1. Ask for the range. A single famous figure, like “a third of Europe”, is often one end of a range. The useful question is what the other estimates are, and why they differ.
2. Check the date of the earliest record. The rhyme first appears in English in 1881 and the beak mask in the seventeenth century. A story about the 1340s needs a source from the 1340s, or close to it.
3. Separate one account from many. The Caffa corpses come from one writer who was probably not there. That does not make the story false, but it is a reason to hold it loosely.

Sources

• Stephanie Haensch et al., “Distinct clones of Yersinia pestis caused the Black Death”, PLoS Pathogens 6(10) (2010), e1001134.
• Kirsten I. Bos et al., “A draft genome of Yersinia pestis from victims of the Black Death”, Nature 478 (2011), 506–510.
• Maria A. Spyrou et al., “The source of the Black Death in fourteenth-century central Eurasia”, Nature 606 (2022).
• Katharine R. Dean et al., “Human ectoparasites and the spread of plague in Europe during the Second Pandemic”, PNAS 115(6) (2018); and Park et al., reply, PNAS 115(34) (2018).
• David M. Bland et al., “Yersinia pestis can infect the Pawlowsky glands of human body lice and be transmitted by louse bite”, PLoS Biology 22(5) (2024).
• Marcel Keller et al., “Ancient Yersinia pestis genomes from across Western Europe reveal early diversification during the First Pandemic (541-750)”, PNAS 116(25) (2019).
• Simon Rasmussen et al., “Early divergent strains of Yersinia pestis in Eurasia 5,000 years ago”, Cell 163 (2015).
• Kathryn A. Glatter and Paul Finkelman, “History of the Plague: An Ancient Pandemic for the Age of COVID-19”, The American Journal of Medicine 134(2) (2021).
• Remi Jedwab, Noel D. Johnson and Mark Koyama, “The Economic Impact of the Black Death”, Journal of Economic Literature 60(1) (2022), 132–78 (abstract; quotations from the 2020 working paper, GWU IIEP 2020-14).
• Remi Jedwab, Noel D. Johnson and Mark Koyama, “Negative shocks and mass persecutions: evidence from the Black Death”, Journal of Economic Growth 24(4) (2019), 345–395 (abstract; “about one half” and the 1348 bull from the 2017 working paper, MPRA 78630).
• Mark Wheelis, “Biological Warfare at the 1346 Siege of Caffa”, Emerging Infectious Diseases 8(9) (2002), including Rosemary Horrox’s translation of Gabriele de’ Mussi.
• World Health Organization, “Plague” fact sheet (29 September 2026).
• Giovanni Boccaccio, The Decameron, introduction to the First Day, trans. J. M. Rigg (London: A. H. Bullen, 1903), Project Gutenberg edition.
• Ordinance of Labourers (1349), as printed by The Avalon Project, Yale Law School, under the title “The Statute of Laborers; 1351”, from Statutes of the Realm i. 307; dated 1349 in Statutes of the Realm vol. 1 (1810).
• Christine R. Johnson, “How the Black Death made life better”, Department of History, Washington University in St. Louis (18 June 2021).
• “The Black Death and the Jews, 1348–1349 CE”, Internet Jewish History Sourcebook, Fordham University, from Jacob Marcus, The Jew in the Medieval World (1938), with the chronicle of Jacob von Königshofen.
• Fitzwilliam Museum, University of Cambridge, “The Flagellants”.
• Edward Maunde Thompson (ed.), Adae Murimuth Continuatio Chronicarum; Robertus de Avesbury De Gestis Mirabilibus Regis Edwardi Tertii (Rolls Series, 1889), editor’s introduction.
• Stephen Winick, “Ring Around the Rosie: Metafolklore, Rhyme and Reason”, Folklife Today, Library of Congress (24 July 2014).
• Kate Greenaway (illustrator), Mother Goose or the Old Nursery Rhymes, Project Gutenberg edition.
• Marion Maria Ruisinger, “Die ‘Pestarztmaske’ im Deutschen Medizinhistorischen Museum Ingolstadt”, NTM 28(2) (2020), 235–252.
• The Public Domain Review, “Plague Doctor Costumes”.
• Gregory IX, Vox in Rama (13 June 1233), in Monumenta Germaniae Historica, Epistolae saeculi XIII, vol. 1, ed. Carl Rodenberg (1883), no. 537.

Checked October 2026. If you can show any of these wrong, with a source, we want to see it: [email protected].