Let's not forget the ethnic cleansing in China, similar cleansing of the Rohyinga in Burma, open slave markets in Libya, etc. etc.

Human nature hasn't hasn't changed, we just ran out of easy to settle real estate. And it's not cost effective to go after easily settled areas -- a couple of world wars showed how ugly that can get.

Once climate change starts changing things I'm sure we'll see yet more "colonization" and unpleasant behavior.