In pre-Islamic times the Arabian Peninsula had rarely been at the center of Middle Eastern events. An immense coastline made the land accessible to and from the Red Sea on the west, the Persian Gulf on the east, and the Indian Ocean on the south, but the real estate of that vast, inhospitable ocean of sand held little strategic interest for the regional powers. Local kingdoms had ruled to the north, in Syria, and to the southwest, in the Yemen. Although the Greeks and Romans knew about the place and liked its incense, they never set their sights on the territory.

When Muhammad was growing up, an important trade route ran up and down the western coastal region, a highway for exchange from Abyssinia (Ethiopia) and the Yemen, to Syria and points north by way of Mecca. To the northwest of the peninsula, the Christian Byzantine empire ruled. To the northeast, in Persia, the Zoroastrian Sasanian empire had displaced the Parthians, a client state of Rome, in 226 C.E. These two “confessional” (i.e., religiously connected) empires had been engaged in a protracted tug-of-war over the Fertile Crescent with its enormous river systems. Two Arab tribes in adjacent states did much of their fighting for them, namely the Monophysite Christian Ghassanids for Byzantium and the unchurched Lakhmids for Persia. As it turned out, their ongoing struggle would pave the way for the early expansion of Islam. By the time Muhammad died, Byzantium and Persia had all but spent themselves into bankruptcy and had so worn each other down that neither would mount serious resistance when the Muslim tribes advanced out of Arabia in a conquering mood.