There's the figure of speech "to tap-dance around (a topic)" meaning to make concerted effort avoid talking about a particular topic all the while talking about many things that are adjacent to that topic. It's usually to avoid coming across as offensive or ignorant in some way.
The underlying cause and/or whether a bit more knowledge on the part of the speaker could render the dance unnecessary is highly contextual (and mostly irrelevant here), but nevertheless, people tap-dance around topics all the time. (The previous sentence might even qualify as an instance.)
So, the question is: How much contribution to this n-gram is people pointing out that someone is, or was, tap-dancing around a topic?
Well, once you've had your country invaded by rabid psychopaths, there's bound to be some gene admixture (to put that far too mildly) and so you've a chance that their descendents, even if it's recessive and rare, will have the desire go on to do the same.
Of course, rabid psychopathy and the urge to invade other places can also come about on its own, but when you look at the way the Vikings and their Germanic cousins invaded western Europe a thousand years or so ago, and then note what happened a few hundred years later, it has to make you wonder whether it might have only happened the once.