Al-Andalus is the name given to the territories of the Iberian Peninsula governed by Muslims between 711 and 1492. At first it covered much of the Iberian peninsua and was known as a province of the Omeya Caliphate (711–756). Gradually, as Christian forces recaptured parts of the territory, the Muslim area became smaller: the Emirate of Córdoba (756–929), the Caliphate of Córdoba (929–1031), the taifa kingdoms and a part of north African Empires (1031-1252) and, finally, the Kingdom of Granada (1252-1492). Over the same period, several Christian kingdoms were established as they conquered the Muslim-controlled areas. These forces advanced along three main lines: the Castilians in the centre of the peninsula, the Aragonese and Catalans in the east, and the Portuguese in the west. In 1212, the defeat of the Muslim armies at the Battle of Navas de Tolosa gave these kingdoms control of the whole of central Spain and this led to the conquest of the main Muslim capitals: Cordoba (1236) and Seville (1248). The alliance between the two great Christian kingdoms, symbolically sealed by the marriage of the Catholic Monarchs, Ferdinand of Aragon and Isabela of Castile, completed this process and Granada was annexed in 1492.