The Middle East is a region where the some of the earliest empires began. The floodplains of the Nile, the Euphrates and the Tigris have sustained the production of food surpluses for millennia. Collected as taxation, at first in kind and later also in coin, these surpluses supported the armies upon which all empire ultimately depends, as well as the religious and political elites who create and maintain an empire's cultural and institutional identity. With the growth of long-distance trade – itself often stimulated by the dynamics of empire formation – revenues from control of trade routes and their entrepôts also became important. Ancient Middle Eastern societies became highly socially stratified: landowning and mercantile elites, and specialists in administrative, military and religious power, were dependent upon the great majority, the subsistence agriculturalists, who farmed the surrounding countryside. Military expansion, and the coercion of neighbouring groups into the provision of tribute and services or more complete incorporation into the empire's tax structure, was typical of these ‘tributary empires’. By the beginning of the first millennium ce, much of the Middle East was ruled by two long-standing such empires. The Parthian Empire (247 bce–c. 224 ce) was centred on the Iranian plateau, but also encompassed most of what is now Iraq, as well as modern Armenia and Azerbaijan. By the early first century ce, the neighbouring Roman Empire had encircled the Mediterranean, encompassing Gaul and Britain in the far north-west and Anatolia, Egypt and Syria in the east.

In the third century ce, both the Iranian and Roman empires weathered major crises. In Iran, the Parthians were replaced by the Sasanian dynasty (r. c. 224–c. 650), a powerful landholding family from the highland region of Fars, in the south-west. The Sasanian Empire competed with Rome with renewed vigour, notably under Shapur I (r. c. 240–c. 270). At the same time, the Sasanian elite negotiated a new relationship with the priests of the Zoroastrian religious tradition of Iran, transforming diverse traditional practices into a more centralised, imperial cult (though not an exclusive one – the Sasanian Empire was multi-confessional, with large communities of Jews, Buddhists, Christians, Manichaeans and others subordinate to the Sasanian aristocracy).