Plague of Justinian

A pandemic caused by the bacterium Yersinia pestis that began in the Byzantine Empire in 541 and recurred around the Mediterranean for more than two centuries.

Yersinia pestis: A bacterium that causes plague in humans and other mammals. Ancient DNA identified this pathogen in people who died during the pandemic.
Plague of Justinian origins: The historical and scientific investigation of where the first pandemic emerged. Its precise geographic origin remains uncertain despite genetic and textual evidence.
Justinian I: Byzantine emperor from 527 to 565 who sought to restore Roman imperial power. The pandemic’s conventional name comes from his reign, when its first outbreak struck.
Byzantine Empire: The medieval continuation of the Roman Empire, centered on Constantinople. Repeated outbreaks occurred within its territories and affected its capital.
Pelusium: An ancient Egyptian port city near the eastern edge of the Nile Delta. Historical accounts place an early outbreak there before plague reached Constantinople.
Bubonic plague: A form of plague marked by painful, swollen lymph nodes called buboes. This clinical form is commonly associated with the pandemic, alongside other forms of plague.
Tian Shan: A major mountain range in Central Asia spanning parts of several modern countries. Ancient plague lineages from Central Asia inform hypotheses about the pandemic’s eastern source.
Procopius: A sixth-century Byzantine historian whose works describe Justinian’s reign and its crises. His account is a key contemporary source for the outbreak in Constantinople.
Constantinople: A historic city on the Bosporus that served as the Byzantine imperial capital. The city experienced a severe outbreak in 542, described by contemporary chroniclers.
Alexandria: A major Egyptian Mediterranean port founded by Alexander the Great. Its commercial links and reported outbreaks connect Egypt to the pandemic’s wider spread.

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