Final answer:
The Black Death, or bubonic plague, is believed to have originated in Asia and then spread to Europe, Africa, and other parts of the world. It was caused by the bacterium Yersinia pestis and transmitted by fleas that infested black rats. The first outbreak was difficult to pinpoint but indications point to a high death rate in Central Asia in 1338 and 1339.
Step-by-step explanation:
The Black Death, also known as the bubonic plague, is believed to have originated in Asia and then spread to Europe, Africa, and other parts of the world.
The disease was caused by the bacterium Yersinia pestis, which was transmitted by fleas that infested black rats.
It is difficult to determine the exact date and location of the first outbreak, but there are indications that there was an abnormally high death rate near Lake Issyk-Kul in Central Asia in 1338 and 1339.
From there, the plague spread eastward, southward, and westward, causing devastating mortality.