Mohammed (ca. 570-632) was the founder of the religion of Islam and of a political unit at Medina that later developed into the Arab Empire, or Caliphate, and a multitude of successor states.

Arabia lay on the periphery of the two empires, the Byzantine and the Persian (Sassanian), which in the early 7th century controlled most of the region from the eastern Mediterranean to India. During the 6th century each made many efforts to gain advantages in Arabia at the expense of the other. From 572 until 628 there was almost constant war between the two, and this left the Byzantine Empire exhausted and the Persian on the point of collapse. This factor contributed largely to the rapidity of the Arab military advance into Persia, Iraq, Syria, and North Africa between 634 and 650.

The town of Mecca, where Mohammed was born about 570, was a commercial center which by 600 had gained monopolistic...