The Umayyads

After the death of Mohammed in 632 AD, the leadership of the new religion, and of the newly united Arab tribes, was taken over by Mohammed's upper-class father-in-law (through his second wife) Abu Bakr. Mohammed left no sons, and in any case there was no tradition of sons taking over in the Arab world. Abu Bakr only lived for two years after becoming Caliph, but he managed to unite the whole Arabian Peninsula under Islam.

There was a rebellion of the Arab tribes after Mohammed's death, which is called the Ridda. With their leader gone, they wanted to go back to being independent. Abu Bakr took an army and succeeded in destroying the Ridda and bringing those Arab tribes back under Islamic control.

Almost immediately after becoming the Caliph, or ruler, in 634 AD, the second Caliph Umar led Arab raids into both the Roman and the Sassanid empires. Both were surprisingly successful. Apparently both the Romans and the Sassanians were much weaker than the Arabs thought they were. Umar was assassinated in 644 AD, and succeeded by Uthman. Encouraged by these early victories, Uthman and his army organized a real campaign, and by 651 AD they took over most of Western Asia, from the Mediterranean coast to eastern Iran.
Uthman was assassinated in 656, and succeeded by Ali, who had a somewhat more radical view of the Islamic faith. Under Ali, the soldiers of the Islamic Empire fought their way through Egypt and North Africa, and although Ali was assassinated in 661, the armies continued and then crossed the Straits of Gibraltar to attack Spain in 710 AD.

After the death of Ali, there was a bitter religious and political struggle between the followers of a more traditional Islamic faith, who were called Sunnis, and the more radical followers of Ali, who were called Shiites (SHE-eye-ts). The Sunnis won, and established the Umayyad dynasty, with its capital at Damascus in Syria.

In Jerusalem, the Umayyads built the first major mosque, the Dome of the Rock, on the site of Solomon's Temple (and the place where Abraham almost sacrificed Isaac). They began building it in 687 AD and finished it in 691 AD.

The Umayyad advance was eventually stopped in several places. In the West, the Romans stopped Islamic attacks against Constantinople in 674-678 and again in 717 AD. The Frank Charles Martel, grandfather of Charlemagne, turned back a series of Islamic raids into France in 732 AD. In the East, the Islamic Empire came up against the Tang Dynasty Chinese, who were also expanding their empire at this time. Though the Arabs won a great battle against the Chinese in 751, near Samarkand in Central Asia, the border stayed about the same from then on.