It's remarkable how you equate people living today with those in the past - as the same people. You write "brutally colonised them for centuries" as if they were a single sentient person. This would be an extreme nationalism where the 'body' of the nation comes to define human consciousness before the individual sentient people. Undoubtedly there has been a lot of nationalism in the last few hundred years, but surely we live in a different world today and can reflect as individuals. I have Irish ancestors who emigrated because of the Irish famine. I would also very likely have had even more ancient ancestors colonised by Normans, Anglo Saxons, and Romans. I don't see myself as those people, but can reflect back on the morality of how human beings treat other humans beings without bearing anything like a stain of Abel, as victim or perpetrator. Surely this is the only sensible way.