The Black Death was one of the most devastating pandemic

Pandemic

A pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...

s in human history

History of the world

The history of the world or human history is the history of humanity from the earliest times to the present, in all places on Earth, beginning with the Paleolithic Era. It excludes non-human natural history and geological history, except insofar as the natural world substantially affects human lives...

, peaking in Europe between 1348 and 1350. Of several competing theories, the dominant explanation for the Black Death is the plague theory, which attributes the outbreak to the bacterium Yersinia pestis

Yersinia pestis

Yersinia pestis is a Gram-negative rod-shaped bacterium. It is a facultative anaerobe that can infect humans and other animals....

. Thought to have started in China, it travelled along the Silk Road

Silk Road

The Silk Road or Silk Route refers to a historical network of interlinking trade routes across the Afro-Eurasian landmass that connected East, South, and Western Asia with the Mediterranean and European world, as well as parts of North and East Africa...

 and reached the Crimea

Crimea

Crimea , or the Autonomous Republic of Crimea , is a sub-national unit, an autonomous republic, of Ukraine. It is located on the northern coast of the Black Sea, occupying a peninsula of the same name...

 by 1346. From there, probably carried by Oriental rat fleas living on the black rat

Black Rat

The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...

s that were regular passengers on merchant ships

Cargo ship

A cargo ship or freighter is any sort of ship or vessel that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's seas and oceans each year; they handle the bulk of international trade...

, it spread throughout the Mediterranean

Mediterranean Basin

In biogeography, the Mediterranean Basin refers to the lands around the Mediterranean Sea that have a Mediterranean climate, with mild, rainy winters and hot, dry summers, which supports characteristic Mediterranean forests, woodlands, and scrub vegetation...

 and Europe.

The Black Death is estimated to have killed 30–60 percent of Europe's population, reducing the world's population

World population

The world population is the total number of living humans on the planet Earth. As of today, it is estimated to be  billion by the United States Census Bureau...

 from an estimated 450 million to between 350 and 375 million in the 14th century.