Before the time of Muhammad, Arabia was inhabited by Bedouin. The city of Makkah was a religious and commercial center. The History of Islam begins in Arabia in the 7th century. At that time the Arabs followed various polytheistic religions; a few of them followed Judaism, Christianity (including the followers of Nestorius) and Zoroastrianism.
Muhammad was born in the year 571 (Common Era, or CE). His father died before his birth, and his mother died at a very early age, so he was raised by his uncle Abu Talib. When he was about 25 years old, Muhammad married a wealthy widow, Khadija, who was 40, and began his career as a trader. Fifteen years later, according to Islamic tradition, he experienced his initial prophetic call, while meditating alone inside a cave in the hills above Makkah - a city in the Arabian peninsula.
Muslims believe that Muhammed was chosen by God, like prophets before him, to teach a sacred message. Though marginalized and opposed initially, Muhammad began to gain followers, most of whom came from lower classes and marginalized peasantry. The first wealthy men accepting the prophet-hood of Prophet Muhammad were Abu Bakr and Umar.
As Islam attracted more believers, Muhammad encountered severe opposition by residents of Makkah who felt threatened because Islam undermined the pagan idols around the Ka'aba. The pagan idols around the Ka'aba were important to the residents of Makkah not only for religious reasons, but also for economic reasons. As pilgrims visited the idols in Makkah, they brought economic prosperity to the city, and the fear was that a monotheistic religion would remove this source of prosperity and trade.
As Muhammad's opponents in Makkah - including one of his uncles, Abu Lahab, who was among his worst enemies - began to organize to bring about an end to his prophecy, Muhammad withdrew with many of his followers to Medina in September of 622 CE. This migration is called the Hijra, and its year is used to establish the Muslim calendar; The year 622 CE is the year 1 A.H. (Annus Hegirae). The A.H. system dates from the beginning of the lunar year in which the Hijra took place, so it does not neatly coincide with the Julian or Gregorian year numbers. After three major battles and one last battle with Makkah, almost all Arabia fell to Muhammad in 630 and great number of tribes established alliance with the prophet.
After Muhammad's death on June 8, 632 CE, Abu Bakr was accepted as caliph, or head of the Islamic state. The next three caliphs were all relatives of the prophet, but were succeeded by another household of the same Makkan tribe, a change not universally accepted, leading to the major division in Islam between the Sunnites (in the majority) and the Shiites (in the minority). The new household was the first major caliphate dynasty, the Umayyads, who conquered the Sassanian empire (Persia) and the southern Byzantine provinces as far as Spain. See also Ali Ben Abu Talib
Most Muslims believe that when Muhammad died in 622, he did not name a successor. The next four leaders of Islam are known as the Four Rightly Guided Caliphs. Abu Bakr was the first as he was the oldest and seen as the wisest; he was Muhammad's father-in-law, and he laid foundations for the years ahead uniting the tribes of Arabia under Islam. Umar was next, and he conquered Persia, Syria, Egypt, and northern Africa. After him came Uthman, who conquered even more territory and developed a navy based in Alexandria, Egypt. Within three generations the Muslims had gone from being a group of wandering camel-herders to being in charge of the largest empire the world has ever known.
When Uthman died, Ali Ben Abu Talib became Caliph. Ali was a cousin and son-in-law of Muhammad. Ali was the husband of Fatima Zahra, Muhammad's daughter. There are people that believe that he should have been the first Caliph because he was named by the prophet. This was rejected by the majority of Muslims who said that the best person for the task of leader should be chosen. His supporters were known as Shi'a ul Ali, (of Party of Ali) or Shi'a for short. The Shi'a believe that the other three Caliphs were illegitimate because they were not named by the prophet. Over time, differences between Shi'a Muslims and Sunni Muslim rose to the level of them practically becoming separate faiths. Some Sunni leaders hold that Shi'a is not truly a form of Islam (and vice-versa). These are, however, the minority of the leaders. In some Arab nations open warfare has erupted between Sunni and Shi'a. In Iraq, the secular Sunni government has oppressed the Shi'a majority. In Iran the religious Shi'a majority made life difficult for Sufi, Sunni and other Muslims. In Saudi Arabia, the religious Sunni majority made life difficult for Shi'a Muslims.
The majority of this new empire was of course non-Muslim, and aside from a protection tax (jiszya) the conquered people found their religions tolerated. Nonetheless the new religion penetrated deeply, to the point where conversions were discouraged since they might have been motivated by avoiding taxes, rather than true belief, and choosing a religion should override such economic concerns. At the same time the Umayyads had dedicated their prestige to conquering the Byzantine empire, and started running into real opposition from the Orthodox provinces. Thus there was a revolution in 750 CE, and a new dynasty, the Abbasids, took the caliphate, marking the transition to a more settled empire.
The political unity of Islam began to disintegrate. The emirates, still recognizing the theoretical leadership of the caliphs, drifted into independence, and a brief revival of control was ended with the establishment of two rival caliphates: the Fatimids in north Africa, and the Umayyads in Spain (the emirs there being descended from an escaped member of that family). Eventually the Abbasids ruled as puppets for the Buwayhid emirs.
A series of new invasions swept over the Islamic world. First, the newly converted Seljuk Turks swept across and conquered most of Islamic Asia, hoping to restore orthodox rule and defeat the Fatimids but soon falling prey to political decentralization themselves. After the disastrous defeat of the Byzantines at the Battle of Manzikert (1071 CE) the west launched a series of Crusades and for a time captured Jerusalem. Saladin however restored unity, defeated the Fatimids and recaptured the city, and later crusades accomplished little other than the looting of Constantinople, leaving the Byzantine empire open to conquest.
Meanwhile, though, a second and far more serious invasion had arrived: that of the Mongols, who conquered most territories up to the borders of Egypt, and permanently ended the Abbasid caliphate. Their wanton destruction left the Islamic world damaged and confused. However it reached a new peak under the Ottoman empire, a tiny state in Turkey that conquered the Byzantines and extended its influence over much of the Muslim peoples.
In the 18th century there were three great Muslim empires: the Ottoman in Turkey, the Middle East, and the Mediterranean; the Safavid in Iran; and the Mogul in India. By the end of the 19th century, all three had been destroyed or weakened by massive influence of Western civilizations.
Muhammad ibn Abd al Wahhab (1703-1792) led a religious movement in the east of Arabia that saw itself as purifying Islam. His most important follower was the then leader of the family of ibn Saud, which came with massive funding and political support. This movement is controversial among Muslims, as its adherents claim to follow the Quran and Sunnah while rejecting traditional Islamic scholarship regarding Fiqh. But so, too, do other movements in more modern Islamic philosophy, some of which claim also to be purifying or restoring Islam, in particular, to be renewing ijtihad. See also: Islamism
Dynasties of Islamic Rulers