Soon after the death of Justinian, there arose in the great desert of Asia one who presented himself to the Arabs as the "Prophet of the One God." This was Mohammed, who was born at Mecca and became a shepherd and, a camel-driver. Before his time the Arabs were idolaters, and to Mohammed they owe their religion and their place in history. His enemies caused him to flee from Mecca to Medina, and this event is called the Hegira. From its date (622) Muslims all over the world reckon all historical events, as the Christians reckon dates from the birth of Christ.
Mohammed himself owed much to the teachings of the Jews and to the Christians. He believed he was destined to complete the revelations of Abraham, Moses, and Jesus, and he was convinced that he was a prophet of God or Allah (Old Testament, Elohim). His teachings were collected in the Koran, as his book is called. All the faithful were enjoined to recite the one-sentence creed: "There is one God, Allah, and Mohammed is His Prophet." They must pray five times a day; fast and give alms to the poor; make a pilgrimage to Mecca; and abstain from strong drink and swine flesh. All worship of idols and relics was forbidden. Women were to be kept in seclusion. His religion is called Islam, which means "submission" (to Allah).
After several years of war, with 10,000 followers Mohammed captured Mecca, and soon the new creed had won all Arabia. Then the faithful began to force their faith upon all "unbelievers." His successors, or Caliphs, conquered and converted a great empire, which formed a crescent, with one horn touching the Black Sea and the other Gibraltar (itself a Moorish name): Persia was conquered; Jerusalem (637) and Alexandria (641) and Carthage (698) all fell before them. They even conquered Spain from the Goths (by 711), and made several raids over the Pyrenees into the heart of France.
Then Europe was for the time saved, for in the west they were overthrown at the great battle of Tours (732) by Charles "the Hammer," one of the successors of Clovis; in the east they had besieged, but failed to take, Constantinople (717).
But the earlier followers of Mohammed were not merely keen warriors. They also did much for civilization. Their two great centres, Bagdad in the east and Cordova (Spain) in the west, were more cultured and more wealthy than any city in Christian Europe at the time. They carried on the learning and arts of the East, and they made themselves masters of the rich trade with India. They excelled in mathematics, astronomy, and medicine. In the beautiful Alhambra at Cordova, and in their many mosques, we can still see their rich architecture.
Their romantic literature is known to the world through the Arabian Tales. These are tales of the time of the great Caliph, Harounal Raschid (Aaron the Just). He was ruling at Bagdad while Charles the Great, or Charlemagne, was king of the Franks, and these famous rulers of East and West respectively exchanged presents one with the other.
Later, the vast Arab Empire split up into separate states. This prepared a way for fresh nomads from central Asia -- the Turks -- who became converts to Islam. Soon these Turks mastered Bagdad (1058), where their chief took the title of Sultan. Then they conquered Asia Minor, and took the Holy City (1O75), and the Wars of the Cross and the Crescent, known as the Crusades, began. Thus the followers of Mohammed made a vast new empire. In time it covered much of Africa and Asia, and here Islam has remained the religion ever since.