Plague of Justinian

The Plague of Justinian was an outbreak of bubonic plague that reached the Mediterranean in 541 and struck the Byzantine Empire, the Sasanian Empire and much of Europe and the Near East over the following years. It is named after the emperor Justinian I, who caught the disease and survived. It was the first known wave of a pandemic that returned repeatedly for about two centuries, and historians still debate how far it reshaped the late ancient world.

The disease was first recorded in 541 at Pelusium, a port on the eastern edge of the Nile delta in Egypt. Its earlier origins are uncertain; Central Asia and East Africa have both been proposed. From Egypt it travelled along the grain and trade routes of the Mediterranean, carried by rats and their fleas on ships, and reached Constantinople in 542.

The historian Procopius, who was in the capital, described the epidemic in detail: fever followed by swellings in the groin and armpits, delirium, and death within days for many of the sick. At its peak, he wrote, the city lost thousands of people a day, at one point perhaps as many as 10,000, though such figures cannot be checked. Bodies piled up faster than they could be buried and were left stacked in the open. Estimates of the death toll in Constantinople vary, but a loss of around a fifth of its population or more is often suggested. Justinian himself fell ill in 542 and recovered.

By 543 the plague had reached most of the empire and had spread to Italy, Gaul and the Persian lands to the east. Northern Europe and the Arabian Peninsula were still affected in 549. After the first wave, the disease did not disappear. It returned in recurring outbreaks, roughly every decade or two, across the Mediterranean and Middle East until the middle of the eighth century; the last major outbreaks are usually dated to around 750.

For a long time the identification relied on written descriptions. Since the early 2010s, ancient DNA recovered from burials in Bavaria and elsewhere has confirmed that the bacterium Yersinia pestis, the cause of plague, was present, making the outbreak the first securely identified plague pandemic. The strain was distinct from the one behind the Black Death eight centuries later.

Older accounts treated the plague as a demographic catastrophe that killed perhaps a quarter to a half of the Mediterranean population, weakened Byzantium and Persia, undermined Justinian's attempt to reconquer the western provinces and eased the way for the early Muslim conquests of the seventh century. Some recent scholars, notably Lee Mordechai and Merle Eisenberg, have argued that the evidence for such mass mortality is thin and that the effects were more limited and uneven. Others defend a higher estimate. The scale remains genuinely uncertain, and some historians' estimates of total deaths over two centuries of recurrence, 15 to 100 million, are far higher than sceptics accept.

Whatever its scale, the epidemic left a strong impression on contemporaries, who described it as a punishment or a sign of the end times, and it shaped later Christian and Islamic writing about plague. Together with wars and a period of colder climate in the mid-sixth century, it forms part of the troubled backdrop to the end of antiquity.

Our 500 map shows the Byzantine and Sasanian empires shortly before the outbreak, and the 600 map shows the Byzantine Empire after Justinian's reconquests in Italy and North Africa.