Haroun al-Rashid is probably the best-known Caliph but there have been caliphates, starting with the Rashiduns in 632. He is the ruler of the Ummah, an Islamic community ruled by the Shari’ah. Caliphate means “succession” in Arabic and the Caliph (successor to Prophet Muhammed) is the supreme ruler of an Islamic state. Sunnis believe it should be an elected post chosen by Muslims, while Shias believe he should be divinely appointed from the family of the Prophet’s direct descendents. There have been many caliphates: Rashidun, Umayyads, Abbasids, Fatimids, Ottomans, Sokoto and Ahmadiyya, which is still extant, among others. In 1923, after the Ottoman Empire collapsed, Turkish leader Mustafa Kemal Atatürk abolished the Caliphate and founded the Republic of Turkey.
The founder of the Umayyad dynasty Muawiyah, after a bitter power struggle in 661, declared the Caliphate a hereditary office. They were popular rulers, lowering taxes, encouraging local autonomy, granting religious freedom to Jews and Christians. The Caliphate covered North Africa, Spain, Persia and Pakistan. Under them, technology, trade art and culture flourished. In 750, the Abbasids from Mecca deposed the Umayyads and ruled from Baghdad for over three centuries. Under them, the Middle East was the cradle of intellectual and cultural developments. They were followed by the Fatimids. In the 9th century, the Abbasids created the slave army Mamluks who established an Abbasid caliphate in Cairo which they built in the late 10th century. In the 15th century, the Ottoman sultans claimed the Caliphate. After the Russo-Turkish War of 1768–1774, the Caliphs were reduced to holding only temporal power. Around 1880, the Turkish Sultan’s claim to the Caliph’s title was supported by Muslims of British India. The powerful Sokoto Caliphate was founded during the Fulani Jihad in the 19th century in Nigeria. The Ahmadiyya Caliphate (1908–present) is viewed as heretical by mainstream Muslims.
A female caliph or the wife or widow of a caliph is called Calipha. There has only been one calipha in history—Sitt al-Mulk of the Fatimid Caliphate who ruled from 1021 to 1023.