In the modern age, we have all sorts of toys and gadgets that go BOOM.
In Antiquity, how does a vengeful strategos exterminate a place for good? Wholesale slaughter and enslavement works well for the humans and barbaroi. But what of the farms, walls and buildings? Salting a place can only be a metaphorical expression. Salt was worth it's weight in gold back then.
Flooding by redirecting rivers/damming has been done before, but not all places have a large enough body of water near it...
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