Saracens: The Muslim Conquerors
The Muslims were broken into several groups most of which were called Saracens. Soon after the death of Muhammad these groups began raiding and conquering Arabia and then Africa, and later into Europe.
The Saracens controlled most of the Muslim land, but still remained ununited until the Turks, another Muslim group attacked the Byzantine Empire and started the Crusades. The Europeans wanted to destroy these infidels and attacked the Holy land which was controlled by the Saracens, and won the prize after the first war.
The Crusaders felt pretty full of themselves and left several major kingdom-colonies controlled by each of the European powers. The Muslims didn't like this and began some minor raids on each, which only infuriated the Europeans enough to have another Crusade. The next Crusade had less success, since this time more Europeans died and less Saracen-Muslims, and some small fiefs one the boarders were destroyed. But, it was enough for the Crusaders.
After the Crusaders left, the emperor Saladin united the Saracens and attempted to destroy the Christian kingdoms in the south. At first he was successful, and forced out the Crusaders in Africa and Jerusalem, but he was disappointed at Acre. Acre was a central city under Muslim control, which was threatened by the Crusaders. The Crusaders used their siege techniques to bring down the walls and take the city, and Britain's Richard the Lionhearted once again was victorious, with the help of the French.
Richard the Lionhearted asked for peace and a treaty was signed by Saladin. The treaty was short-lived, Richard the Lionhearted ordered the citizens of Acre to be killed. But after more fighting the Crusaders left never to return.
The Saracen kingdom in Spain was taken by the northern Christians led by El Cid, and the Saracen Empire slowly dissolved back to the deserts from whence it came. The Saracens lived on, but no longer as a world power and later they divided into the modern countries in Arabia and north of India, not to be heard from by Europe until WWI.
The pictures at the top from ensemblestudios.com