Islam began in Mecca when the prophet Muhammad began to spread the word of God (292). The Prophet “tried to warn his people against the worship of false gods and all immortality, especially against injustice towards the poor, orphans, widows, and women in general” (293). The first converts to the religion were Meccan citizens and peasants (292). Although some prominent Meccans joined him, the aristocracy generally resisted his teachings (293-94). According to the Quran, heaven lies in gratitude to God as well as in his guidance and forgiveness (293). Muhammad is accepted as the last of many prophets chosen to spread the word of God (293). Unfortunately, the teachings of the Prophets did not spread easily and were not successful (293). However, many peoples followed his wife Khadija and recognized him as a “chosen reformer” (293). After Muhammad's death in 632, the lack of a successor or son led to a political struggle between the Meccan and Medinese peoples. This ended when Abu Bakr was chosen as the Prophet's successor (297). However, as in most previous cases, many Arab tribes renounced allegiance to the Prophet after his death (297). Nonetheless, Abu Bakr's government “re-established religious conformity for much of Arabia and forced the Arabs to recognize the faith and practice of Islam as opposed to a certain leader; the prophet Muhammad in this case” (297)Following Bakr, the caliphs Umar and Uthman pushed the Arab armies beyond the peninsula and conquered the Byzantine and Sasanian territories, Egypt, and much of Iran by 643 (297). This success can be attributed to the leadership of the early caliphs and field generals, as well as the weakness of the Byzantines and Iranians (297). In 651, the Arab armies defeated the last of the Sasanian rulers (297). The Fourth Caliphate; ...... middle of the sheet ...... Sian oppression (298). Muslims accepted other religions and allowed Christian, Jewish, and Zoroastrian groups to live under the protection of Islamic rule “provided they recognized Islamic political authority, paid a non-Muslim head tax, and did not interfere with Muslim religious practices.” (298). The head tax and other divisions on non-Muslims encouraged many to convert (298). Islamic culture was also highly adaptable and open to the fusion of cultural traits, which allowed it to spread even in hostile societies (346). Muslims could exchange ideas and goods with Muslims from radically different backgrounds and “meet them as brothers and sisters of the Ummah” (347). Therefore, Islam spread mainly through the conquests of the Arab armies and spread successfully due to its principles, high adaptability, the weakening of the Byzantine and Sasanian empires, and its immense leadership.