Plague of Justinian

The Plague of Justinian was a pandemic caused by bubonic plague. It happened during the years of 541 to 542 in the Byzantine Empire. It was the first pandemic recorded in history. Historians estimate that this pandemic killed as many as 100 million people across the world, partly because it returned every twelve years until 770, when it stopped for about 500 years.
Between 541 and 700, the Plague of Justinian killed about half of the people in Europe. It also may have contributed to the success of the Muslim conquests. Its social and cultural impact is comparable to that of the Black Death.
Origin and impact.
Through trade, the plague came from India to Ethiopia or Egypt. Eventually, trade ships brought the plague north to the large city of Constantinople. Ships bringing grain, which Constantinople imported, carried rats along with them. These rats carried the plague. By the end of the pandemic, the plague had killed 40% of Constantinople's population. At its worst, it killed 10,000 people in Constantinople every day.
In total, about 25 million people died because of the Plague of Justinian. It is said to have contributed to the fall of the Byzantine Empire, because it killed farmers and caused famine. Also, the empire relied on tax money, and the plague killed many taxpayers.