The historical divide of Islam into Sunni, or so-called orthodox Islam, and Shia, was caused more by political dispute over successors than doctrinal differences, although differences gradually assumed theological and metaphysical overtones. Despite the split, within centuries Islam reached far into Africa, eastward to the Indian subcontinent and southeast Asia, as well as northward into Central Asia. This expansion was accomplished by traders and missionaries as much as by conquest.

Sunni constitute 85 percent of the world's Muslims; Shia about 15 percent. Each division has four major Shariah or schools of theological law. The Sunni: Hanafi, dominant in the Arab Middle East, India, Pakistan and Afghanistan; Maleki, in north, central and west Africa and Egypt; Shafii, in east Africa, Indonesia and southeast Asia; Hanbali, in Saudi Arabia. The Shia: Ithna Ashariya or Imami, the state religion in Iran, dominant in Iraq and also found in Afghanistan; Nizari Ismaili, present throughout the Muslim world, including Afghanistan, led by the Aga Khan; Zaidiya, in Yemen; Mutazila, in Syria and Lebanon.

Data as of 1997

NOTE: The information regarding Afghanistan on this page is re-published from The Library of Congress Country Studies and the CIA World Factbook. No claims are made regarding the accuracy of Afghanistan Sunni and Shia Islam information contained here. All suggestions for corrections of any errors about Afghanistan Sunni and Shia Islam should be addressed to the Library of Congress and the CIA.