<P> The Almohad dominance of Iberia continued until 1212, when Muhammad al - Nasir (1199--1214) was defeated at the Battle of Las Navas de Tolosa in the Sierra Morena by an alliance of the Christian princes of Castile, Aragon, Navarre and Portugal . Nearly all of the Moorish dominions in Iberia were lost soon after, with the great Moorish cities of Córdoba and Seville falling to the Christians in 1236 and 1248, respectively . </P> <P> The Almohads continued to rule in northern Africa until the piecemeal loss of territory through the revolt of tribes and districts enabled the rise of their most effective enemies, the Marinid dynasty, in 1215 . The last representative of the line, Idris al - Wathiq, was reduced to the possession of Marrakesh, where he was murdered by a slave in 1269; the Marinids seized Marrakesh, ending the Almohad domination of the Western Maghreb . </P> <P> 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 and unifying Muslim lands, Selim I became the defender of the Holy Cities of Mecca and Medina, which further strengthened the Ottoman claim to the caliphate in the Muslim world . Ottomans gradually came to be viewed as the de facto leaders and representatives of the Islamic world . However, the earlier Ottoman caliphs did not officially bear the title of caliph in their documents of state, inscriptions, or coinage . It was only in the late eighteenth century that the claim to the caliphate was discovered by the sultans to have a practical use, since it allowed them to counter Russian claims to protect Ottoman Christians with their own claim to protect Muslims under Russian rule . </P> <P> According to Barthold, the first time the title of "caliph" was used as a political instead of symbolic religious title by the Ottomans was the Treaty of Küçük Kaynarca with the Russian Empire in 1774, when the Empire retained moral authority on territory whose sovereignty was ceded to the Russian Empire . </P>

When did the claim to the caliphate become central to ottoman ideology