Having united most of Arabia under the Islamic banner by 633, Muslim
military commanders began to mount serious expeditions beyond the peninsula,
where only probing attacks had occurred during the lifetime of the prophet and
in the period of tribal warfare after his death. The courage, military
prowess, and religious zeal of the warriors of Islam and the weaknesses of the
empires that bordered on Arabia resulted in stunning conquests in Mesopotamia,
North Africa, and Persia that dominated the next two decades of Islamic
history. The empire built from these conquests was Arab rather than Islamic.
Most of it was ruled by a small Arab-warrior elite, led by the Umayyads and
other prominent clans, which had little desire to convert the subject
populations, either Arab or otherwise, to the new religion.