In the 9th century, al-Andalus stabilised its north-eastern borders near the Ebre and the Segre rivers. Saraqusta (Zaragoza), Wasqa (Huesca), Larida (Lleida), Turtusha (Tortosa) and Balagha (Balaguer) became important cities. In the early 11th century, when the Caliphate began to disintegrate, Larida and Turtusha became centres of political power known as taifas. Under the Almoravids, al-Andalus was once again reunified politically. In the mid-12th century, what had been the northern border of al-Andalus began to cede in the face of attacks from feudal Catalan armies.