The Black Death, also known as the Great Plague, the Black Plague, or simply the Plague, was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people in Eurasia and peaking in Europe from 1347 to 1351. The bacterium Yersinia pestis, which results in several forms of plague, is believed to have been the cause. The Black Death was the first major European outbreak of the second plague pandemic. The plague created a series of religious, social and economic upheavals, which had profound effects on the course of European history.
The Black Death is thought to have originated in the dry plains of Central Asia, where it travelled along the Silk Road, reaching Crimea by 1343. From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships, spreading throughout the Mediterranean Basin and Europe.
The Black Death is estimated to have killed 30–60% of Europe's total population. In total, the plague may have reduced the world population from an estimated 450 million down to 350–375 million in the 14th century. It took 200 years for the world population to recover to its previous level. The plague recurred as outbreaks in Europe until the 19th century.