Sprawling across two million square miles of the earth’s surface, Alexander’s empire (Map 1) was a geographic, ecological, ethnic, and cultural patchwork. Its multiple heartlands (Figure 11) included the rocky but intermittently lush Mediterranean coasts of Greece, Macedonia, and Anatolia; the abundant Nile Valley and Delta; the then “fertile crescent” of present-day Palestine, Lebanon, Syria, and Iraq (watered by the Jordan, Orontes, Tigris, and Euphrates rivers); and, to the east, the high plains of Afghanistan and the vast and verdant Indus Valley.

Densely populated, these regions were ringed and punctuated by high peaks and arid deserts: the mountains of Greece; the dry Anatolian plateau and the Taurus Range that severs it from Syria; the Caucasus, linking the Black and Caspian seas; the Egyptian and Arabian deserts to the far south; the arid and mountainous Iranian plateau; and the mighty peaks of the Hindu Kush.

The Persian kings had controlled most of this vast area for two centuries, ruling a volatile collage of Greeks, Anatolians, Syrians, Phoenicians, Jews, Arabs, Egyptians, Babylonians, Medes, Persians, Baktrians, and Indians – to name but a few. Crisscrossed by a dense web of trade routes, their empire was highly urbanized and divided into two dozen provinces, or satrapies, each ruled by a provincial governor, or satrap (thus, for example, Hellenistic writers called the Iranian plateau the Upper Satrapies). Alexander inherited this system, and his successors happily perpetuated it.