After a succession of Phoenician, Roman, Barbarian and Byzantine rule, in 827 under the Abbasid caliphate, Arabs conquered the island of Sicily declaring Palermo their capital city. Its strategic geographic location linking Islamic and Christian civilizations soon made it one of the most important political and cultural centers of its time, along with Cordoba and Cairo. Its subsequent Aghlabid, and Kalbid (Fatimid) dynasties brought great prosperity to the city by building mosques, palaces, hammam, and other public facilities, and by developing new commercial advancements in the silk, paper, mosaic and shipbuilding industries. By the mid-eleventh century however, internal political stability began to disintegrate and Norman armies from the north overtook Sicily. While Christian in faith, the Norman kings legally protected Sicily's Muslim population. They were known for their tolerance and the multicultural nature of their court, which included poets and scientists from the Islamic world. They ruled the island until 1194, maintaining Palermo as their administrative post and the city continued to prosper under their patronage. Many of Palermo's richest historic monuments were built during this period, including the Cappella Palatina in the Palazzo Reale, San Giovanni degli Eremiti, the Cathedral of Monreale, Palazzo della Zisa and Palazzo della Cuba. Constructed by Arab designers and craftsmen, these sites display the interlacing of Muslim, Roman, and Byzantine stylistic influences so typical of Norman Sicily, producing a distinctive moment in the history of architecture.