The Development of Regional Styles. The disintegration of the khilafah, which began with the independence of western North Africa (modern Morocco and Algeria) as early as 740, continued thereafter at an increasing pace and led to the development of regional architectures, even though Islam remained unified in religion, law, and expressions of spirituality under the banner of Sunnism, reflecting the popular understanding and will. By 900 the political unity of the khilafah was largely broken. From 945 until 1152 the khalifahs did not even rule in Baghdad, and their brief temporal restoration from 1152 to 1258 was purely local and lasted only until the Mongols destroyed the khilafah with the sack of Baghdad. Different styles of architecture developed under the patronage of regional rulers who claimed various degrees of independence from the khalifahs and wanted to show their independence by stamping their monuments...