PBS.org: Islam, followed by more than a billion people today, is the world’s fastest growing religion and will soon be the world’s largest. The 1.2 billion Muslims make up approximately one quarter of the world’s population, and the Muslim population of the United States now outnumbers that of Episcopalians. The most populous Muslim countries are Indonesia, Bangladesh, Pakistan, and India. The number of Muslims in Indonesia alone (175 million) exceeds the combined total in Egypt, Syria, Saudi Arabia, Iraq and Iran, the traditional heartlands of Islam.
There are also substantial Muslim populations in Europe and North America, whether converts or immigrants who began arriving in large numbers in the 1950s and 1960s. In keeping with tradition, the two main branches of Islam today are Sunni and Shiite.
Islam: Empire of Faith is a documentary series, made in 2000, that details the history of Islam, from the birth of the Islamic Prophet, Muhammad to the Ottoman Empire. It is narrated by Ben Kingsley and is available as three DVDs or two video volumes in NTSC format.