"European colonialism has been far and away the worst offender in this regard in the last 500 years. Take a look at this GIF charting the rise and fall of (mostly) European empires from 1492, when the European discovery of the Americas kicked off their movement west and south, to 2008."

Larger image here: http://cdn3.vox-cdn.com/assets/4421631/colonialism.gif
More info here: http://www.vox.com/2014/5/8/5691954/colonialism-collapse-gif-imperialism