The first recorded appearance of the plague in Europe was at Messina, Sicily in October of 1347. It arrived on trading ships that very likely came from the Black Sea, past Constantinople and through the Mediterranean. This was a fairly standard trade route that brought to European customers such items as silks and porcelain, which were carried over land to the Black Sea from as far away as China. The people of Messina were shocked and scared of what sickness had come from the ship that they expelled it from the port, yet it was too late. The plague took over the city, infecting many very quickly. Many panicked and fled, thus, spreading it to the surrounding countryside. The expelled trading ships brought it to other areas around the Mediterranean, infecting the neighboring islands of Corsica and Sardinia by November.
Plague had also traveled from Sarai to the Genoese trading station of Tana, east of the Black Sea. There, Christian merchants were attacked by Tartars, and many fled to their fortress at Caffa. The Tatars surrounded the city in November, yet soon the Black Plague struck and killed off many of the invaders. Before breaking off their attack, however, they catapulted dead plague victims into the city in the hopes of infecting its residents. In panic, the citizens at Caffa threw the bodies into the sea, but the plague had already infected residents and was spreading like wildfire… it was too late. As the inhabitants of Kaffa became infected, the merchants boarded ships to sail home. But they could not escape the plague. When they arrived in Genoa and Venice in January of 1348, almost all the crew was dead, and the survivors were in fear they may contract the disease.
The rapid spread of the plague can be contributed to the filthy conditions the people lived in during those times, especially in Europe. Showers or baths were rare, and if a person did wash themselves up, the water they washed themselves in was dirty. Rats who carried fleas (and the plague) scurried about the streets, and residents rarely if ever tried to kill or get rid of them. Many people wore the same clothes day after day, or lived in small houses with many people, so the disease was easy to catch. There was no FDA, food safety was never regulated, so the plague also spread in that way (the food was dirty and infected).
Like any disaster (man-made or natural) that wipes out a significant portion of a generation or generations of people, there is always speculation regarding "what if" the disease, war, famine, earthquake, etc., did not happen. How would the world be different? Notably, since the Black Death has killed many people, we can infer that the population of the areas affected would be larger in the generations following. Would the prevailing economic and food systems have been able to support a larger group of people? In other words, would more people have meant...