I'm hoping that anyone out there with information about Islam and the Arabs would be willing to help me post stuff here to answer any questions people may have about this part of the world. I'm sure Marina can be particularly helpful.
Islam technically started in the year 622 of the Common Era. It was started by a dude named Mohommed who lived among the Quraysh tribe of Arabic peoples in the town of Medina (Saudi Arabia). Christianity and Judaism was known to them but many people still clung to pagan beliefs. This was known as the time of the "jahaliyya", or "pre-enlightened barbarism".
Mohommed began having "contacs with God (Allah)" in which he basically began speaking of philosophical and political changes that were to take place. These early prophesies were somewhat unfocused and general, yet created a stir in the area. He was run out of town for being something of a rabble-rouser. He fled to the city of Mecca. This pilgrimage to Mecca with his band of followers was the first "Hijra".
In Mecca, Mohommed's prophesies became more clear and focused. He insisted that society should be run in strict orders and that the family was the basis of moral upbringing rather than warlordism. He became something of a militia general and helped fight back marauding bandits that threatened the city many times. He later returned to Medina leading a large force and triumphantly marched into the city.
Mohommed had a wife, Aisha, who was older than he and was at one time his employer (women were allowed business and property rigths, more so than European women). Aisha was frequently visited by people seeking advice and wisdom due to her relationship with Mohommed. People began to wonder if visitors really sought advice or were just comming to hang out with the wife of Mohommed, so it wass decided that she would sit behind a curtain and talk with people, dispensing advice unseen. Thus was born the tradition of the veil as an Islamic feature, although veils had been used in Arabic society before that.
By 633 Mohommed died and there was a conflict in leadership. Two groups disputed who was to lead the "umma", or the "body of the faithful". One group believed that the leadership should go to whoever was the most pious believer in the community, this group was caled "Sunni"; others felt that only a blood relative of Mohommed could lead them: the "Shia'a" or "partisans".
The Sunni voted Abu Bakr as leader. The Shia'a champion, Ali (Mohommed's cousin and the man that married Mohommed's daughter Fatima), would run again three more times and be voted in on the fourth run for office. These religious leaders or "Caliphs" are called the "Rashidun", or the righteously-guided caliphs due to their personal connections to Mohommed.
Things fell apart when Ali was run out of the community for supposedly having murdered the governor of Syria in order to ascend to leadership. The Shia'a were running away when they were attacked by Sunni forces at Karbala, in Iraq. The town became a holy place of martyrdom for the Shia'a everywhere, for Ali (and possibly Fatima) were both killed there. For the Shia'a, Karbala is a city of status close to that of Mecca itself.
The Sunni continued to spread ander various dynasties, first the Umayyid and later Abbasid dynasties based in Baghdad and Damascus. The Shia'a spread through Persia (Iran). In Sunni tradition, the "umma" (faithful people) are expected to read the Qur'an for themselves while the Shia'a believe that it is the job of the Ayatollahs and Mullahs (all of which can supposedly trace their lineage back to Mohommed) to read the Qur'an and interpret it for the people.
The Qur'an, the collected writings of Mohommed's prophesies, contain the supposed words of Allah that Mohommed transcribed. Theya re arranged in chapters or "Surats" from the shortest (one page) to the longest. They are not in any chronological order or related to one another, and the Mecca prophesies are more rambling while the Medina prophesies are more focused. So the book frequently seems to be a bit schitzophrenic.
Also held in esteem are the sayings of the Prophet, or "hadith". These are not words from Allah but thoughts of Mohommed as a man. They are seen as good as holy writ, so long as they do not contradict anything in the Qur'an itself. In Shia'a tradition, the sayings of Fatima and Ali are also seen in this light.
After Islam spread it began to slow down and the courts of the Umayyad and Abbasid dynasties were hotbeds of corruption. Various schools of thought emerged, putting local spin on certain practices and interpreting things in new ways. Religious leaders, called "ulama", began to question and criticize the Hadiths of Mohommed and interpret them in many ways when issuing Fatwas (religious decrees) based on these interpretations.
When the European/Christian West attacked in the Crusades of 1095 (and the sack of Jerusalem in 1099) the Islamic world began to come together as a cohesive unit (it took awhile). European Christians eventually kicked the Muslims out of Spain, but in Constantinople (Turkey) the Turkish Muslims were besieging the last outpost of the Byzantine Empire. By the mid-late 1400's, the Islamic world was more or less onfined to the borders we recognize now.
Much of the area was ruled by the Ottoman Turks, who were seen as the leaders of Islam. A "caliphate" or council of religious leaders was in Istanbul (not Constantinople!