The Fatimid Caliphate was an Islamic caliphate that spanned a large area of North Africa, from the Red Sea in the east to the Atlantic Ocean in the west. The dynasty of Arab origin ruled across the Mediterranean coast of Africa and ultimately made Egypt the centre of the caliphate. At its height the caliphate included in addition to Egypt varying areas of the Maghreb, Sudan, Sicily, the Levant, and Hijaz.

The Fatimids (Arabic: الفاطميون‎, translit. al-Fāṭimīyūn) claimed descent from Fatimah, the daughter of Islamic prophet Muhammad. The Fatimid state took shape among the Kutama Berbers, in the West of the North African littoral, in Algeria, in 909 conquering Raqqada, the Aghlabid capital.

In 921 the Fatimids established the Tunisian city of Mahdia as their new capital. In 948 they shifted their capital to Al-Mansuriya, near Kairouan in Tunisia. In 969 they conquered Egypt and established Cairo as the capital of their caliphate; Egypt became the political, cultural, and religious centre of their empire that developed an indigenous Arabic culture.

The ruling class belonged to the Ismaili branch of Shi’ism, as did the leaders of the dynasty. The existence of the caliphate marked the only time the descendants of Ali and Fatimah were united to any degree (except for the final period of the Rashidun Caliphate under Ali himself from 656 to 661) and the name “Fatimid” refers to Fatimah. The different term Fatimite is sometimes used to refer to the caliphate's subjects.

After the initial conquests, the caliphate often allowed a degree of religious tolerance towards non-Ismaili sects of Islam, as well as to Jews, Maltese Christians, and Egyptian Coptic Christians. However, its leaders made little headway in persuading the Egyptian population to adopt its religious beliefs.

During the late eleventh and twelfth centuries the Fatimid caliphate declined rapidly, and in 1171 Saladin invaded its territory. He founded the Ayyubid dynasty and incorporated the Fatimid state into the Abbasid Caliphate.

Ismāʿīlism (Arabic: الإسماعيلية‎ al-Ismāʿīliyya; Persian: اسماعیلیان‎; Sindhi: اسماعيلي‎; Esmāʿīliyān), or Seveners, are a branch of Shia Islam. The Ismāʿīlī get their name from their acceptance of Imam Isma’il ibn Jafar as the appointed spiritual successor (Imām) to Ja’far al-Sadiq, wherein they differ from the Twelvers who accept Musa al-Kadhim, younger brother of Isma'il, as the true Imām.

Ismailism rose at one point to become the largest branch of Shī‘ism, climaxing as a political power with the Fatimid Caliphate in the tenth through twelfth centuries. Ismailis believe in the oneness of God, as well as the closing of divine revelation with Muhammad, whom they see as "the final Prophet and Messenger of God to all humanity". The Ismā’īlī and the Twelvers both accept the same initial Imams.