Natalie Solent has been further pondering the question of imperialism and colonialism, with a mild but just comment from Gary Farber in mind.
In my defence, I did make reference to the destructiveness of colonialism (with some consequent reflections on the value of democracy) in my 'PS' to the post in question. That was not an afterthought, though it looks like one. Democracy is a fine thing, but it is not absolutely essential to civilisation under all circumstances. The Middle Ages had a civilisation, arguably folk then were even free. But in the current age democracy is necessary to prevent the vast power of the State from being too oppressive to its citizens and dangerous to its neighbours.
But to return to the main point: one would have to have a heart of stone not to be horrified by the doings of wicked white men in the bad old days. One of the books which made a huge impression on me as a child was this one. It's profoundly upsetting, and arguably the Plains Indians weren't the worst sufferers.
Natalie sums up well: "The wheel makes some strange turns."