Columbus Day this year brought with it the usual acrimony, and this Salon article hit the usual talking points by declaring European settlement of the Americas to be "the most massive act of genocide" in world history.
Slate quotes historian David Stannard who writes: "[O]n average, for every 20 natives alive at the moment of European contact — when the lands of the Americas teemed with numerous tens of millions of people — only one stood in their place when the bloodbath was over."
Source: http://www.valuewalk.com/