There was this phrase that really stuck with me- rivers flowing red and black with blood and ink. So both, probably.Well, actually, I hear people mention the loss of life quite frequently. Different backgrounds, I guess.
Most people here think of Genghis Khan and his crew as generic scary but "badass" guys, like, say, King Arthur or a real-life Batman more than Hitler. This is, I think, more because he was not a direct enemy but rather this guy who defeated our culture's historical enemies, and we don't remember them the same way. I haven't heard either lamented very much from the general populace- or from the museums even. The Genghis Khan exhibit focused mostly on how tolerant he was and how he had good battle strategies, etc., not on the immense destruction of culture and life.
Additionally they were not mainly looking to kill people for religion or race, as the Nazis were. The deaths from the Holocaust are so well remembered partially because they were the main point of Hitler's genocide (as with ISIS), and partly because it was closer geographically and chronologically, and partly because, ultimately, Hitler didn't succeed. I'm not sure if the memory of the crimes will fade with time but I certainly hope we will keep the memories alive and "never forget" indeed.
As the effects fade, however, we might forget- but the human effect was much larger than the cultural one is perceived to be and the memories of the lost culture are more likely to fade if anything does; there is not that same level of never forget applied to culture (perhaps because, while Hitler succeeded in killing many, he failed at destroying the Jewish culture and so it is not a thing to be remembered so much as honored or, pertaining to destroyed objects and synagogues and communities, mourned and kept alive with the new).
So back on topic with ISIS, we (not me specifically, the Americans) see them as an extension of AQ and terrorism and were directly "attacked" (I can't find a sufficient word for the beheadings so sorry for the air quotes), so it is possible that their crimes against life will be seen as crimes against us (and our values of free religion, anti-genocide, classic natural rights etc) more than their destruction of Shia shrines, Assyrian structures, Iraqi history etc.
I think the extent to which they will be reviled and for what will be larger and different respectively (this respectively pertains to the terms directly preceding it not after it) among the Shias and Iraqis and etc. than among Americans, ofc, but I'm not in a position to judge or predict what non-Americans will remember.
Whew, that was interesting! Thank you for making me reconsider and analyze things. (Just by the way, you're one of my favorite Paradoxians Wagon, as are you, Panzer.)