The Black Death – everything you need to know

There are so many myths & misconceptions going around about the Black Death that I thought it might be a good idea to put a bunch of facts together.
The topic seems to be extra popular among the creators of AI slop nonsense and they generally keep repeating the same old rubbish, so this article may help you poke holes in what they want you to believe.

Miniature by Pierart dou Tielt illustrating the Tractatus quartus bu Gilles li Muisit (Tournai, c. 1353). The people of Tournai bury victims of the Black Death. ms. 13076 – 13077 fol. 24v.

In this article I’ll debunk several of the claims that are often made, I will mention sources & references in the article but also at the end.
Remember that articles, youtube videos, tiktoks, etc. are worthless if the claims in them are not backed up with evidence.
You can also click some words to go to a wikipedia page that contains some basic information on that particular topic.
Wikipedia is of course not a source but just another article that will contain sources and references in case you want to learn more, either way, it’s more reliable than 99% of random blogs people usually share online.
Use it more like a dictionary or encyclopaedia entry.

Warning: the topic is rather gruesome, links may take you to websites with horrific images and stories.

Important: scientific, historical and archaeological research continues and new discoveries keep coming in, so this article is a work in progress.
When new evidence is found and published that changes what we know, I’ll update the article.

Latest update: 4th June 2026

What the Black Death is:

The Black Death is not a disease, it’s an outbreak of a disease, in this case the plague, Black Death is the name we’ve given the pandemic.
This naming happened centuries later, medieval people didn’t call it that.
If someone is writing an article or making a video and they call it the Black Plague, you know they’ve not done their research.
It’s a common mistake to make but an inexcusable one for content creators, writers, etc.

The Black Death was likely a combination of the 3 known types of plague:

Bubonic Plague
Most common, infection takes place mostly in the lymphatic system and this causes lymph nodes to become painful, dark and as big as an egg, sometimes even an apple.
Septicaemic Plague
In this case the infection reaches the patients bloodstream and will turn parts of the body (especially toes and fingers) to go black and die.
Pneumonic Plague
The worst kind, but luckily also very rare.
This one infects the lungs, which means it can then be spread through coughing and sneezing.

Plague is still around and regularly makes people sick and in some cases can still be deadly.
Large scale outbreaks are rare, but still happen, in 2017 over 200 people died of pneumonic plague in Madagascar.

What causes the plague:

Bubonic and Septicaemic plague are caused by the Yersinia Pestis bacterium that causes the digestive tract of its host, a flea (or possibly also a louse), to get blocked, this causes the bug to vomit the next time it tries to suck a human blood.
This is how bug vomit with plague as extra ingredient enters the body.

Dance of Death, leaf from “The Nuremberg Chronicle”, by Michael Wolgemut, 1493

Where the plague come from:

The Yersinia Pestis bacterium has been around for thousands of years, current scientific research suggests that it originated in Central Asia, specifically the Tian Shan mountain region of Kyrgyzstan/Kazakhstan.
It originated with rodents in that region, not rats but marmots.
This is where it likely first infected cattle and then humans in prehistoric times.

What caused the Black Death outbreak:

The plague had broken out many times in the region where it originated but it would usually burn out before it could be spread very far, with other words, some people would get sick but then die before others got infected.
In the 1330s the marmots and their fleas came in contact with humans again, possibly because weather had either caused marmot numbers to explode or extremely diminish, both cases would have resulted in fleas needing to find new hosts, as they had done for centuries, but this time something changed.
Trade routes went through this area, travellers following for instance the famous silk road had passed here but in the 1330s the Pax Mongolica caused even more trade and traffic and also large groups of quickly moving refugees and armies.
This all caused many more people moving through the place when another plague outbreak happened.
But these people didn’t stay put, they moved on, giving the fleas and the bacterium a lift.
Increased traffic of humans and goods from the Tian Shan mountain region of Kyrgyzstan/Kazakhstan to the rest of the known world would cause the deadliest pandemic in human history.

Detail of the Catalan Atlas depicting Marco Polo travelling to the East during the *Pax Mongolica*.

Catapulting bodies:

There’s a famous story about Mongol attackers catapulting the bodies of dead plague victims over the walls into the city of Caffa/Kaffa (today Feodosia) during a siege, many claim that this might be the first case of biological warfare, but we don’t really know if this happened and it probably didn’t.
According to the story the dead bodies caused the plague to spread within the city and/or cause so much panic that people fled on ships, spreading the outbreak to Europe.
The story is based on one single account written by Gabriele de Mussi from Italy in 1348, originally historians believed this to be a reliable eyewitness account but later they discovered that Gabriele never even left his hometown, he was never near the actual siege.
This means that there is no reliable, contemporary evidence for this event.
Trade routes seem to have played a bigger role in how the plague reached Europe than this particular siege.
For a plague victim to be used in this manner it has to be fresh, as soon as a body starts cooling down the fleas will move on, within hours.
When a body explodes on impact and you are standing nearby with your mouth open, you can also get sick, but the odds of that are minimal.
So even if they had catapulted dead bodies, it may not have had much of an effect.
Their evil plan would have only worked if they used fresh bodies with fleas still on them, something nobody back then knew.
Some claim that they also wouldn’t have done this because of religious reasons (they had recently converted to Islam) or because of emotional reasons towards their recently departed brothers in arms, but I doubt that, extreme situations test morals beyond breaking point and they may have had access to non-Muslim, non-Mongol bodies.
The story sounds like just a typical made up claim about how brutal and barbaric the enemy, those people with a different religion, those scary uncivilised other folks, are.
It’s not to be taken seriously, at least not till more evidence is found.
Either way, the catapulting during this one siege, if it happened or not, is not what caused the plague to spread to the rest of the world.

How it spread:

For a long time it was believed that the Black Death outbreak was caused by rats giving fleas a ride around the world, but recent evidence has shown that this is unlikely as the plague travelled too fast for this.
The real reason it spread was because of humans, fleas (and likely lice) would bite humans, live in their hair, their woollen clothes, even some of the goods they were transporting.
This is how it moved from east to west, from Asia, to the Middle-East, Africa and eventually ending in Western-Europe.

From ‘The Complete History of the Black Death’ by Ole J. Benedictow, 2021

The Black Death decimated African cities like Cairo, Alexandria, Tunis, Fez, Tiemcen, Ceuta, Marrakech, Constantinople etc.
In the middle east it hit Mecca, Aleppo, Damascus, Homs, Hama, Baghdad, Jerusalem, Gaza, Medina etc.
Some of these got the black death before W-Europe did.
The mortality rates in these cities were just as high or worse than several European cities, Cairo was especially hard hit, perhaps harder than any other city.

From ‘Annales de démographie historique’ by Stuart Borsch

The cure:

There was no cure, outrunning it and going into isolation was the only possible way to avoid it and even then you still had to get lucky.
It didn’t matter how much you washed or bathed, how many rats there were in your city, which religion you had, etc.
Muslims, Jews, Christians, they all got it at equal rates and they all died at equal rates.
Death did not care who you were, what you believed in, your skin colour, your gender, your age, your wealth or how clean or dirty you were.
Of course being extra weak would not have helped, had you for instance just experienced a famine or another disease, your odds would be bad.

It is often claimed that quarantine was invented at this time, but the idea of isolating sick people goes back much further (it’s even in the bible) and the official system that gave the process its name didn’t really seem to have gotten off the ground till a few decades after the Black Death.
Making sure visitors from other places were kept separate for a while was a good idea though and one of the few things that worked, the bacterium needed to stay on the move and when the fleas (and humans) who got sick died there would be nowhere for it to go.

The first cure for plague that became available is the antibiotic Streptomycin which was discovered in the 1940s, these days doctors use Gentamicin.
Luckily people whose ancestors had survived earlier plague outbreaks developed a level of resistance against it, but nobody saved anyone by bringing them the cure or teaching them basic hygiene during the middle ages.

The connection to hygiene:

The Black Death is often named in discussions about hygiene in Medieval Europe, but that is often based on the outdated idea that it was spread by rats and that it was an European disease.
People imagined medieval cities being overrun by rats, rats are attracted by bad hygiene and rubbish, so it makes sense that people once believed it but it is nonsense.
As already explained, the disease originated in Asia and was killing millions there, the Middle Eat & Africa, it was killing Muslims and Jews as well as Christians.
So if it was because of bad hygiene, everyone on those continents had bad hygiene.
But it wasn’t because of bad hygiene.
Fleas don’t care how often you bathe, wash or clean your house and street, soap and cleanliness won’t keep them from biting you.
Today we can keep fleas away thanks to pesticides, vacuum cleaners, chemicals & better isolated houses, but even today you will be bitten by a flea a few times in your life.
Medieval people could not get rid of fleas and lice, they tried very hard, but it was impossible to completely avoid them, just before the middle ages, just like centuries after the middle ages and even like today.

The killing of the cats:

The popular claim that Europeans were so superstitious ( and stupid) that they killed all the cats, which resulted in rats populations exploding in size, transporting more fleas and thus causing more people to die of the plague.
This is nonsense.

As I explained already, the plague was mainly spread by fleas on humans, not (just) rodents.
Cats are not very good at keeping the human population down.
Although there were plenty of cases of people being cruel towards cats and suspicious of black cats, there is also lots of evidence of people loving cats, just like today.
Cats were also very important in the eternal fight against vermin that kept trying to steal food.
There’s no evidence of anyone killing cats on a massive scale, a decretal letter written by a pope is often mentioned in these claims, but he just wrote about a weird cult that did silly things with a statue of a cat, but he never called on Christians to go slaughter the cats.
But even if people had started killing cats, it wouldn’t have made a difference.
Fleas also travelled on cats and they are highly susceptible to plague and are a common source of infection in humans.

How many died:

It is impossible to say how many people actually died of the Black Death.
Records are often incomplete or vague.
Research has long been Eurocentric and only relatively recently have historians and archaeologists started investigating the spread of the Black Death on other continents.
In many parts of the world people were not keeping any records at all and human remains are sometimes the only evidence there even is of the plague reaching those places.
We know that the mortality rate was extremely high, we know that many millions died, but the total number is an educated guess.
It took decades for the world to recover, entire towns were abandoned and in some cities half or even more of the inhabitants had died.
Sometimes calculations involve looking at population numbers before and after the plague but even then the best we can do is come up with very rough estimates.
Currently the number of Black Death victims is somewhere between 75 and 200 million people worldwide.

The plague doctor

The famously intimidating plague doctor with the bird beak mask has nothing to do with the Black Death.
It didn’t exist at the time and didn’t even exist during the entire middle ages.
The only convincing evidence of the plague doctor outfit even existing at all, comes from the writer Michel de Saint-Martin who in his 1682 biography of Charles de Lorme, the chief physician of three French kings mentions the special outfit the doctor had made and wore during the 1618/19 plague outbreak in Paris.
There may have been another one in use in Italy a while later but there’s no evidence of anyone anywhere wearing it besides these two cases.
So not only was it not medieval, it was also extremely uncommon.

The consequences:

The Black Death changed the world and in some ways we’re experiencing its effects to this day.
For the direct survivors, who of course had to deal with traumas we can barely even imagine, in some ways, at least at first, things often changed for the better, but what really happened is often exaggerated.
Yes there of course really was a severe shortage of labourers which resulted in workers being able to bargain for better wages.
And yes, half of even your entire family dying did result in you likely inheriting land, goods and even money from not just your parents but also uncles, aunts, etc.
However, these advantages were not available to everyone and they often didn’t last very long.
It is sometimes said that the plague ended serfdom in Europe but that’s too optimistic a claim.
The upper classes fought hard to bring things back to the way they are and in some ways they succeeded.
The gains peasants obtained because of the Black Death rarely lasted very long.
In Eastern Europe things were almost the opposite, here the nobility took advantage of the situation to increase their power over the peasants.

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