The world of Classical Antiquity was in its geography and in the range of its diseases restricted compared with the world of today. Largely confined to the Mediterranean basin for most of our period, it was also relatively free from large incursions of outsiders bringing with them unfamiliar pathogens. 1 Traders might reach as far as China, Malaya and Zanzibar, and sail from N. Africa round the northern tip of the British Isles, but these were exceptions. 2 For the most part, home was around the inland sea, 'our sea' as the Romans called it. Even when the armies of the Roman Empire reached the Danube, the Elbe and the Tigris, and when soldiers from Spain, Syria and Dacia stood guard on Hadrian's Wall, mixing with vendors and camp-followers who had come from even further afield, from Commagene in modern Turkey or Palmyra in the Syrian desert, the pattern was not radically altered. 3 Travel was slow, whether on foot, on horseback or by sea, and fear of winter storms often closed the Mediterranean for weeks. Consequently, the world-view of the average man or woman was confined to the farm, the village or the nearest large town. Those who ventured from one part of the ancient world to another were relatively few. Only armies and, in the last two centuries BC, captives destined to be sold as slaves in the markets of Delos or Rome moved in large numbers over great distances.
Large-scale concentrations of population were also rare. Before 330 BC, only a few places, notably Athens, Corinth, Syracuse (Sicily) and Carthage (Tunisia), had more than 15,000 inhabitants. Many so-called 'Greek cities' would have had fewer than 2,000 persons living within their walls, with more beyond them in the surrounding countryside, but rarely exceeding 6,000 in all. 4 The number of large cities grew in the Hellenistic and Roman period, including Alexandria (Egypt), Antioch, Ephesus and Smyrna (all in modern Turkey), and Rome itself, whose population has been estimated at between 750,000 and 2 million by AD 10, but these were exceptional. Reasonably exact figures are hard to obtain even from the more detailed data supplied by Egyptian papyri, but those that have been proposed, based on a variety of types of evidence drawn from all over the ancient world, give a sense of the order of magnitude involved. 5 They confirm the earlier pattern: most of the population lived in what we