While in a conversation recently, I came up with the expression for something I had always felt for.
Notwithstanding all the advances in civilization and awareness through media, people haven't got "life to be fair" even today. Why do we expect it to be fair 50, 500, 1000 or (even more so) 2000 years ago! Without realizing this, we are trying to (a) ascertain the winners and losers of the past conflicts (b) judge the conflicts' rationale in light of modern day morality and common sense (c) determine the descendants of the affected parties and (d) invariably demand or try to amend the injustice dealt.
What this exercise does is to bitter people towards other social groups, be these cast or religion based. People will become xenophobic fearing a repeat of what has happened some 500 years ago. An action and its retaliation will only affirm their fears, in turn making things worse.
I do not think I am in a position to suggest a solution. More able people have been trying to do this for thousands of years and more effectively so since the dawn of mass media. All I suggest is that when you look at an past event, please put yourself in that context and then only judge the events. An objective appraisal will score even higher.