The Fatimids established the Tunisian city of Mahdia and made it their capital city, before conquering Egypt and building the city of Cairo there in 969. Thereafter, Cairo became the capital of the caliphate, with Egypt becoming the political, cultural and religious centre of the state. Islam scholar Louis Massignon dubbed the 4th century AH /10th century CE as the "Ismaili century in the history of Islam". The term Fatimite is sometimes used to refer to the citizens of this caliphate. The ruling elite of the state belonged to the Ismaili branch of Shi'ism. The leaders of the dynasty were Ismaili imams and had a religious significance to Ismaili Muslims. They are also part of the chain of holders of the office of the caliphate, as recognised by some Muslims. Therefore, this constitutes a rare period in history in which the descendants of Ali (hence the name Fatimid, referring to Ali's wife Fatima) and the caliphate were united to any degree, excepting the final period of the Rashidun Caliphate under Ali himself. The caliphate was reputed to exercise a degree of religious tolerance towards non-Ismaili sects of Islam as well as towards Jews, Maltese Christians and Copts. The Shiʻa Ubayd Allah al-Mahdi Billah of the Fatimid dynasty, who claimed descent from Muhammad through his daughter, claimed the title of caliph in 909, creating a separate line of caliphs in North Africa. Initially controlling Algeria, Tunisia and Libya, the Fatimid caliphs extended their rule for the next 150 years, taking Egypt and Palestine, before the Abbasid dynasty was able to turn the tide, limiting Fatimid rule to Egypt. The Fatimid dynasty finally ended in 1171 and was overtaken by Saladin of the Ayyubid dynasty. Ayyubid Caliphate (1171–1260) The Ayyubid Empire overtook the Fatimids by incorporating the empire into the . However, Saladin himself has been a widely celebrated caliph in Islamic history. Ottoman Caliphate (1517–1924) The caliphate was claimed by the sultans of the Ottoman Empire beginning with Murad I (reigned 1362 to 1389), while recognising no authority on the part of the Abbasid caliphs of the Mamluk-ruled Cairo. Hence the seat of the caliphate moved to the Ottoman capital of Edirne. In 1453, after Mehmed the Conqueror's conquest of Constantinople, the seat of the Ottomans moved to Constantinople, present-day Istanbul. In 1517, the Ottoman sultan Selim I defeated and annexed the Mamluk Sultanate of Cairo into his empire. Through conquering