Most people know about the Black Death. The plague that swept through Europe in the mid 14th century and killed somewhere between a third and half of the European population. It is one of the most covered events in medieval history.
What most people do not know is that a very similar pandemic hit the world eight centuries earlier and may have been just as deadly.
It is called the Plague of Justinian. And it is one of the most significant events in ancient history that almost nobody learns about.
What It Was
The Plague of Justinian was the first recorded pandemic caused by the bacterium Yersinia pestis, the same organism responsible for the Black Death. It began in 541 AD during the reign of the Byzantine Emperor Justinian I, from whom it takes its name.
The plague likely originated in central or east Africa and spread along trade routes through Egypt into the Byzantine Empire and beyond. It reached Constantinople in 541 and spread across the Mediterranean world.
At its peak in Constantinople the plague was reportedly killing 10,000 people per day. Emperor Justinian himself contracted the disease and survived but barely. By some estimates the city lost 40 percent of its population.
The pandemic spread throughout the Byzantine Empire, into Persia, across North Africa, into western Europe. It persisted in recurring waves for roughly two centuries, flaring up every few years until around 750 AD.
Total deaths are estimated at somewhere between 25 and 50 million people. In a world with a much smaller total population than today that represented an enormous fraction of all living humans.
What It Changed
Justinian had been on the verge of reuniting the old Roman Empire. He had already reconquered North Africa from the Vandals and was making significant progress in Italy and Spain. The Plague of Justinian killed the soldiers, the farmers, and the tax payers that made those campaigns possible.
The reconquest of the western Roman Empire was abandoned. The Byzantine Empire contracted. The power vacuum in the west allowed new kingdoms and peoples to establish themselves permanently.
The Arab expansion of the 7th century, which transformed the entire Mediterranean world, happened in part because the Byzantine and Persian empires had both been severely weakened by the plague. Populations that had been devastated were less able to resist conquest.
The Plague of Justinian is not just a historical curiosity. It fundamentally shaped the world that came after it. The reason Europe in the medieval period looked the way it did, the reason the Byzantine Empire was what it was, the reason the Arab expansion succeeded as quickly as it did, all trace back in part to the pandemic of 541 AD.
And it is barely in any history curriculum in the western world.
Robert Lee Beers III is a writer and digital preservation advocate based in North Charleston South Carolina.
