Carthage alone was absolutely ploughed about, but the notion of it remaining salted won't flip up right until the nineteenth century. Carthage was almost certainly not salted right after the Third Punic War, and neither was Milan by Frederick Barbarossa above a thousand many years later on. The thought seems to appear from confusion over a Medieval buy contacting for the city of Palestrina to be ploughed over "like Carthage", and also salted.