When Europeans came to the Americas they brought with them diseases that are endemic in their societies. These diseases largely came from domestic animals they lived in close association with. Some 10 diseases, including small pox and measles, were illnesses Native Americans had no resistance to, not having had exposure to them before. It is estimated that there was a mortality rate of 95% in some places, largely from the diseases, but also augmented by the maltreatment the conquerors inflicted. Imagine 95% of everybody you know dying.
