Islam's expansion throughout Asia, Africa, and parts of Europe are credited to conquest and the belief that Muslims had the responsibility of converting nonbelievers to Islam, known as Jihad. Although conquest appears to be part of the early Islamic and Christian faiths, scholars believe that Islam was accepted, in part, due to the fact that Christians, Jews, and Muslims worship the same God.
Islam embraced many ethnicities, and an early tax on nonbelievers encouraged some to convert to the faith. Some believe that the conquest of Egypt and Syria were successful due to fact that residents were weakened and defeated by other wars.
Like other religions, however, Islam was divided over the fact that some believe that the ruling elite should be Arab or descend from the family of the prophet.