The origins of the Black Death is said to have happened in Central Asia and the Steppes. There would have been a mutation in some bacteria that affected rats. These rats were infected with fleas, which also contracted Black Death. These fleas were the vectors to transport the disease to humans from the rats. The Mongolian Empire was the first civilization to reap what happened from this epidemic. Mongolian towns were completely wiped out, and the visitors to these towns would take the valuable items, not knowing it was infected. This allowed the plague to spread along the Mongolian Empire, and finally along the trade routes into Europe.

Many doctors and religious leaders credited the plague to one of two things; either God sent down this plague and this was the start of the apocalypse, or that the planetary alignment produced some bad gases in the air, which spread the plague. The former was widely accepted, which led to the reaction of religious zealots and the Flagellants made their appearance, hoping that hurting themselves would show forgiveness from God. This caused a widespread debate on how to follow religion during the plague. The latter, bad gases, was actually more realistic, as this was what was accepted by many scientists. While not correct at all, it led to the wearing of facemasks and taking cautious measures against the environment, which actually helped in slowing down the spread of the plague.

Other practices to combat the plague were things such as quarantine, cordon sanitaires, no freedom, etc. These were also effective in slowing down the plague from spreading since there was not much contact between towns and cities thanks to the shutting down of cities, and for those who were affected by the disease were not allowed to have human contact. This was also effective in slowing down the plague until the plague was no longer a large issue in Europe, other than some more flare ups in future cities and towns.