Now this is a good debate.

Personally, my view is that it is inappropriate to hold people from past generations to modern value systems, as the rational basis of those modern values did not exist yet.

We only expect human rights because we have ancestors that fought for them. Before the conflicts became commonplace, part of being a "good" person was to behave differently. We should not think that we are somehow special and would behave any differently than our ancestors, had we been nurtured in that time, surrounded by only those antiquated ideas.

This is why Genghis Khan and Hitler should be seen in a different light. They were both butchers, but the Khan was a butcher in a time of butchers. Where Hitler did it in a time of industrialization and the rise of globalization. One of the men is a respected historical figure of great relevance, the other is despised as one of the most evil men in history. Not for different actions, though, but for doing the same actions in different contexts, in worlds of different expectations.