Plato's account of the Atlantis story probably isn't that reliable because the philosopher was not recognised as a chronicler and in all probability had misquoted his sources. Secondly the philosopher was known to spin a bit of a yarn now and then in order to demonstrate a particular philosophical point and this very much appears to have been what had happened in the case of his Atlantis story. The philosophical discussion in question at the time had been what exactly constitutes an ideal society?
Indeed Plato's Atlantis was hardly an ideal society by today's standards anyway. The society he describes was a completely feudal one where the arable land is divided into set allotments each of which has the role of supporting a given military unit. Further it is clear the island is governed by kings and is not therefore democratic in any way. Some may find this surprising as the age that Plato lived in in ancient Greece did in fact have many democratic ideals. The fact that Atlantis was feudal would also strongly suggest that the islanders were extremely war-like as feudalism is a system which is designed to support and maintain an active war machine.
The date Plato gives for the destruction of the island, 9,000 B.C., is also a little challenging. The philosopher claimed to have obtained his story from a source in Egypt and in this land they sometimes recorded the passing of time in 'seasons' rather than years. There were three seasons in an Egyptian year which would tend to make Plato's 9,000 B.C. look more like 3,000 B.C. This roughly tallies with the very beginning of Egyptian history and pre-dynastic times.
But what of Plato's description of the exact layout of the lost city of Atlantis? Had the philosopher perhaps been thinking of ancient Carthage situated on the north coast of Africa? This harbour town had a feature in it consisting of a concentric ring of water with a further hill overlooking this. The Carthaginians were a sea-faring nation of Phoenician origin and they had made Carthage a major power within the Mediterranean. But of course when Plato had been writing the Carthaginians would still have been an important power to be reckoned with.