The Justinian Plague was a devastating pandemic that struck the Byzantine Empire during the reign of Emperor Justinian I in the 6th century. It is believed to have originated in Central Asia and spread through trade routes, affecting major cities like Constantinople. The plague was caused by the bacterium Yersinia pestis, which is also responsible for the later Black Death. This outbreak began in 541 AD and recurred in waves for nearly two centuries, leading to significant population decline and social disruption. Estimates suggest that millions of people died, profoundly impacting the economy and the structure of society in the Byzantine Empire and beyond.