It started in China in the early 1330's. The plague mainly affected rodents and fleas, but since China did trades with Asia and Europe, these countries were soon also affected.
In 1347, Italian merchant ships returned from the Black Sea to Europe. Many on board were already dying from the plague.
The fleas began to affect Europe's people, which allowed it to spread rapidly among the people.
The Bubonic plague was a period in history when Europe and much of the world's population was reduced.
