system
A chat on subreddit /r/NoStupidQuestions
human
Conquest and enslavement was not seen through a modern day lens of morality. These people didn't think what they were doing was evil, because in their frame of reference, their acts were not evil. 

You can't impose modern day viewpoints on historical figures.
gpt
Now I do think people are sometimes too eager to view historical events and people through a modern lens... but do you *really* think people didn't think conquest was bad back then? Even if their opinion on it wasn't *as* negative as it is today, I guarantee you the people being conquered never enjoyed it.