The Black Death

The Black Death, also known as the Black Plague,
Great Plague or simply Plague, was one of the most devastating
pandemics in human history, The bacterium Yersinia pestis,
which results in several forms of plague,
is believed to have been the cause.[4]
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 then 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 and Europe.

The Black Death is estimated to have killed 30–60%
of Europe's total population.[6] In total, the plague may have reduced the
world population from an estimated 450 million down to 350–375 million
in the 14th century.[7] It took 200 years for the world population to recover
to its previous level.[8][9]
The plague recurred as outbreaks in Europe until the 19th century.

A: The first historical record of bubonic plague is in
Central Asia in 1338/39. It reached China and Indiaby 1346.
It infected the Black Sea port of Kaffa by 1347.
One (false) legend says that the Mongols infected the city
of Kaffa by shooting infected corpses over the walls with
catapults.

During the Middle Ages, bubonic plague, known as the "Black Death,"
killed thousands of people. Bubonic plague is a potentially fatal bacterial
infection called "Yersina pestis." ... These photos show
what infection with bubonic plague looks like, and
also some of the ways it is transmitted from animals to humans.