The bubonic plage reached Europe because of poisoned rats that got into peoples food and houses that spread to entire cities all over europe and the fact that made it worse was that people through out there fecies outside. What the bubonic plague did to the population was shrink because people who got the plague diedt.
The Bubonic Plague arrived on trading ships that very likely came from the Black Sea, probably through the Mediterranean.
Pandemics and epidemics cause a lot of harm to the environment, and kills a lot of livestock and wildlife. One of the upsides, however, is that most people are now immune to large-scale diseases such as smallpox and other deadly diseases that in the past caused a lot of death.
Hope this helps!
