A more robust written record informs McNeill’s study of disease patterns starting from 500 B.C. By this time, civilization flourished along several well-known and fertile river basins, but there were general rules to the limits of their expansion, many of them explained by disease. In the ancient Middle East, literary sources such as the “Epic of Gilgamesh” and the Old Testament reference familiarity with society-altering diseases, though only through modern deduction may it be determined which those diseases were, and what the real-world context for them might have been. The Assyrian and Persian empires flourished well before the period described in this chapter, and with any such flourishing, “it follows that epidemic diseases of the sort that attracted the attention of biblical writers were neither severe nor frequent enough to threaten the fabric of civilized society with disruption” (97). In such stable civilized disease environments, once-epidemic disease patterns become more fragile “childhood diseases,” analogous (and sometimes identical) to such modern-day diseases as measles and chicken pox.

Geography made a critical difference in the spread of disease, and McNeill focuses on three distinct geographical areas.