[geezer]

People are and have never been squeamish about killing. They just don't like to witness gore in their own backyards while they are enjoying brunch with their families. Concentration camps eliminate the inconvenience of having your day ruined by unsightly executions by moving the fate of undesirables out of your sight.

And regarding Mongols, most of what you learn from history is greatly exaggerated. Mongols fought to conquer and the cheapest way to conquer is to intimidate the enemy. It was in their interest to spread terror through stories of murder and brutality and it was in the interest of their victims to spread the same stories to elicit sympathy.

[RcouF1uZ4gsC]

They also backed up their reputation for brutality with stuff like https://en.wikipedia.org/wiki/Siege_of_Baghdad_(1258)

Their actions severely depressed to population of the area for centuries.

[emodendroket]

I don't know that I agree with the parent's conclusions, but it is certainly true that people in the past were much more used to seeing death, whether of humans or animals.