The Black Death (aka the bubonic plague) first entered Europe in 1347 and was widespread across the continent by 1350. The disease was carried by infected fleas on the backs of rats onto various ships in Asia, which in turn entered European ports and then spread from person to person along nearly every one of Europe’s major trade routes. The greater the volume of human contact during any sort of connected economic transactions, the greater the transmission and the faster the spread of the disease. The spread of the Black Death was helped along by several other internal factors within the continent as well – frequent crop failures had been devastating the region for a few years. These failures, in turn, caused widespread malnutrition, hunger, and famine among much of Europe’s population, especially in the cities – which were also hotspots of trade, further compounding the dire situation. Prior to the plague’s arrival, Europe had also been struggling with a chronic over-population dilemma, which put further strains upon the already diminished food supply and the overall state of ill-health. Taken together, these factors coalesced to create the perfect conditions for the horrifically rapid spread of the Black Death throughout Europe.

In the 1330s an outbreak of Bubonic plague began in China. By the mid-fourteenth century it had spread throughout Eurasia, leading to widespread sickness and death. The Black Death, as it came to be called in Europe, led to the death of perhaps as many as one hundred million people and caused the population of Europe to decline by one-third.

When the Europeans arrived in the Americas in the late fifteenth century the differences between civilization in South America and North America could be summarized as follows - South America contained more multinational empires and tended to be based on extensive agricultural systems and permanent settlements; whereas North America contained much smaller and more homogeneous communities who were more likely to live a nomadic, hunter-gatherer type lifestyle. Of course this distinction is not uniform and has many notable exceptions.

To begin with an "epidemic" is a widespread infectious disease. Throughout human history epidemics have had a diverse impact on human society. They have destabilized governments, encourage revolutions, spurred socioeconomic change, limited and encouraged the exchange of ideas, led to a decline in trade, and had many other unexpected consequences.

The Mississippian civilization arose in pre-Columbian America around 700 CE. The people of the Mississippian civilization built earthen mounds for religious and ceremonial purposes. Their largest city was called Cahokia. They declined, however, more than two centuries before the arrival of Europeans in the Americas.

Although it is true that the Mississippian civilization declined in the thirteenth century, we cannot say for sure that it was a result of prolonged famine and drought. No-one knows exactly why the Mississippian civilization declined, but it is certain that it did so long before the arrival of Europeans in the fifteenth and sixteenth centuries.