The Black Death was a plague pandemic that occurred in Europe from 1346 to 1353. It was one of the most fatal pandemics in human history, leading to the death of up to people, around 30% to 60% of the European population and approximately 33% of the Middle Eastern population. The disease was caused by the bacterium Yersinia pestis, which is primarily spread by flea bites, though it may also spread through contact with infected tissues or fluids and, in pneumonic cases, through respiratory droplets.
The Black Death had far-reaching population, economic, and cultural effects. It has been tentatively considered as the second plague pandemic, despite each of these outbreaks being separated by around 500–600 years.
The Black Death was the second great natural disaster to strike Europe during the late Middle Ages (the first one being the Great Famine of 1315–1317). There were further outbreaks throughout the Late Middle Ages. Due to the crisis of the late Middle Ages, the European population did not regain its 14th century level until the 16th century. Outbreaks of the plague recurred around the world until the early 19th century.
Names European writers contemporary with the plague described the disease in Latin as or ; ; . In English prior to the 18th century, the event was called the "pestilence" or "great pestilence", "the plague" or the "great death".John of Fordun's Scotichronicon ("there was a great pestilence and mortality of men") Subsequent to the pandemic "the furste moreyn" (first murrain) or "first pestilence" was applied, to distinguish the mid-14th century phenomenon from other infectious diseases and epidemics of plague.
The 1347 pandemic plague was not referred to specifically as "black", at the time, in any European language. The expression "black death" had occasionally been applied to other fatal or dangerous diseases. In English, "Black death" was not used to describe this plague pandemic, however, until the 1750s; the term is first attested in 1755, where it translated .
This expression, as a proper name for the pandemic, had been popularised by Swedish and Danish chroniclers in the 15th and early 16th centuries, and in the 16th and 17th centuries, it was transferred to other languages as a calque: , , and .The German physician Justus Friedrich Karl Hecker (1795–1850) cited the phrase in Icelandic (), Danish (), etc. See: Previously, most European languages had named the pandemic a variant or calque of the .
The phrase 'black death', describing Death as black, is very old. Homer used it in the Odyssey to describe the monstrous Scylla, with her mouths "full of black Death" ().Homer, Odyssey, XII, 92. Seneca the Younger may have been the first to describe an epidemic as 'black death' (), but only in reference to the acute lethality and dark prognosis of disease.Seneca, Oedipus, 164–170. The 12th–13th century French physician Gilles de Corbeil had already used to refer to a "pestilential fever" () in his work On the Signs and Symptoms of Diseases (). The phrase , was used in 1350 by Simon de Covino (or Couvin), a Belgian astronomer, in his poem "On the Judgement of the Sun at a Feast of Saturn" (), which attributes the plague to an astrological conjunction of Jupiter and Saturn.On page 22 of the manuscript in Gallica (), Simon mentions the phrase ('black death'): ('When the king ended the oracles of judgment / Black Death arose, and the nations surrendered to him'). A more legible copy of the poem appears in: See also: His use of the phrase is not connected unambiguously with the plague pandemic of 1347 and appears to refer to the fatal outcome of disease.
The historian Elizabeth Penrose, writing under the pen-name "Mrs Markham", described the 14th-century outbreak as the "black death" in 1823. The historian Cardinal Francis Aidan Gasquet wrote about the Great Pestilence in 1893 and suggested that it had been "some form of the ordinary Eastern or bubonic plague". In 1908, Gasquet said use of the name for the 14th-century epidemic first appeared in a 1631 book on Danish history by J. I. Pontanus: "Commonly and from its effects, they called it the black death" ().
Previous plague epidemics
Research from 2017 suggests plague first infected humans in Europe and Asia in the Late Neolithic to Early Bronze Age. Research in 2018 found evidence of Yersinia pestis in an ancient Swedish tomb, which may have been associated with the "Neolithic decline" around 3000 BCE, in which European populations fell significantly. This Y. pestis may have been different from more modern types, with bubonic plague transmissible by fleas first known from Bronze Age remains near Samara.
The symptoms of bubonic plague are first attested in a fragment of Rufus of Ephesus preserved by Oribasius; these ancient medical authorities suggest bubonic plague had appeared in the Roman Empire before the reign of Trajan, six centuries before arriving at Pelusium in the reign of Justinian I. In 2013, researchers confirmed earlier speculation that the cause of the plague of Justinian (541–549, with recurrences until 750) was Y. pestis. This is known as the first plague pandemic. In 610, the Chinese physician Chao Yuanfang described a "malignant bubo" "coming in abruptly with high fever together with the appearance of a bundle of nodes beneath the tissue". The Chinese physician Sun Simiao who died in 652 also mentioned a "malignant bubo" and plague that was common in Lingnan (Guangzhou). Ole Jørgen Benedictow believes that this indicates it was an offshoot of the first plague pandemic which made its way eastward to Chinese territory by around 600.
Origin The origin of the Black Death is disputed. Genetic analysis suggests Yersinia pestis bacteria evolved approximately 7,000 years ago, at the beginning of the Neolithic, with flea-mediated strains emerging around 3,800 years ago during the late Bronze Age. The immediate territorial origins of the Black Death and its outbreak remain unclear, with some evidence pointing towards China, Central Asia, West Asia, and Europe. The pandemic was reportedly first introduced to Europe during the siege of the Genoese trading port of Caffa in Crimea by the Golden Horde army of Jani Beg in 1347. From Crimea, it was most likely carried by fleas living on the black rats that travelled on Genoese ships, spreading through the Mediterranean Basin and reaching North Africa, West Asia, and the rest of Europe via Constantinople, Sicily, and the Italian Peninsula. There is evidence that once it came ashore, the Black Death mainly spread from person-to-person as pneumonic plague, thus explaining the quick inland spread of the epidemic, which was faster than would be expected if the primary vector was rat fleas causing bubonic plague.
A 2026 study published in Nature identified the oldest known evidence of plague outbreaks in human remains, finding traces of Yersinia pestis DNA in the teeth of 18 ancient hunter-gatherers from four cemeteries near Lake Baikal in Siberia. Carbon dating revealed two outbreaks, with the earliest cases dating to approximately 5,500 years ago, some 200 years earlier than previously established. Researchers concluded the disease likely spread initially from marmots through contact with raw organs or infected hides, and also transmitted between people through respiratory means. Many victims were young children, with three young girls buried side by side among the dead.
There has been a quest to find "patient zero", the earliest known victim(s) with evidence of the Black Death.The Black Death: Patient Zero TV Documentary, Apple TV, 2025 In 2022, in an article called "The source of the Black Death in fourteenth-century central Eurasia", researchers pointed to the earliest victims of the plague found at two cemeteries in the Chüy Valley near Lake Issyk-Kul in modern Kyrgyzstan. Here graves had tombstones with Syriac inscription, providing the name of the deceased, year of death and often the cause of death, showing a spike due to "pestilence" in 1338–1339. The article reported DNA data to provide genetic evidence from the teeth of seven individuals from the two cemeteries at Kara-Djigach and Burana finding evidence of Yersinia pestis. This confirms that the Yersinia pestis strain found in Kyrgyzstan predates and was the direct ancestor of the Black Death strains that devastated Europe and the Middle East starting in 1346–1347.
Causes
Early theory
A report by the Medical Faculty of Paris stated that a conjunction of planets had caused "a great pestilence in the air" (miasma theory). Some Muslim doctors cautioned against trying to prevent or treat a disease sent by God. Others adopted preventive measures and treatments for plague used by Europeans. These Muslim doctors also depended on the writings of the ancient Greeks.
Predominant modern theory
Due to climate change in Asia, rodents began to flee the dried-out grasslands to more populated areas, spreading the disease. The plague disease, caused by the bacterium Yersinia pestis, is enzootic (commonly present) in populations of fleas carried by ground rodents, including marmots, in various areas, including Central Asia, Kurdistan, West Asia, North India, Uganda, and the western United States.
Y. pestis was discovered by Alexandre Yersin, a pupil of Louis Pasteur, during an epidemic of bubonic plague in Hong Kong in 1894; Yersin also proved this bacterium was present in rodents and suggested the rat was the main vehicle of transmission. The mechanism by which Y. pestis is usually transmitted was established in 1898 by Paul-Louis Simond and was found to involve the bites of fleas whose midguts had become obstructed by replicating Y. pestis several days after feeding on an infected host. From p. 674: "Nous avon pratiqué un certain nombre de fois l'examen microscopique du contenu intestinal des puces recueillies sur les rats spontanément pestiférés, et dans plusieurs cas nous avons constaté la présence d'un bacille morphologiquement semblable à celui de la peste." ("We carried out a number of times microscopic examinations of the intestinal contents of fleas [which were] collected from rats [which had become] infected with plague, and in several cases we noted the presence of a bacillus [which was] morphologically similar to that of the plague.") This blockage starves the fleas, drives them to aggressive feeding behaviour, and causes them to try to clear the blockage via regurgitation, resulting in thousands of plague bacteria flushing into the feeding site and infecting the host. The bubonic plague mechanism was also dependent on two populations of rodents: one resistant to the disease, which act as hosts, keeping the disease endemic, and a second that lacks resistance. When the second population dies, the fleas move on to other hosts, including people, thus creating a human epidemic.
DNA evidence
Definitive confirmation of the role of Y. pestis arrived in 2010 with a publication in PLOS Pathogens by Haensch et al. They assessed the presence of DNA/RNA with polymerase chain reaction (PCR) techniques for Y. pestis from the tooth sockets in human skeletons from mass graves in northern, central and southern Europe that were associated archaeologically with the Black Death and subsequent resurgences. The authors concluded that this new research, together with prior analyses from the south of France and Germany, "ends the debate about the cause of the Black Death, and unambiguously demonstrates that Y. pestis was the causative agent of the epidemic plague that devastated Europe during the Middle Ages". In 2011 these results were further confirmed with genetic evidence derived from Black Death victims in the East Smithfield burial site in England. Schuenemann et al. concluded in 2011 "that the Black Death in medieval Europe was caused by a variant of Y. pestis that may no longer exist".