<P> During its history, the society of the pre-modern Islamic world was dominated by two important social contexts, nomadic life and Urbanism . The historian and politician Ibn Khaldun thoroughly discusses both concepts in his book Muqaddimah . According to him, the way of life and culture of the rural bedouin nomads and the townspeople are opposed in a central social conflict . Ibn Khaldun explains the rise and fall of civilizations by his concept of Asabiyyah ("bond of cohesion", or "family loyalty"), as exemplified by the rule of the caliphs . Bedouins, being the nomadic inhabitants of the steppe and the desert, are interconnected by strong bonds of asabiyyah and firm religious beliefs . These bonds tend to slacken in urban communities over some generations . In parallel, by losing their asabiyyah, the townspeople also lose the power to defend themselves, and fall victims to more aggressive tribes which may destroy the city and set up a new ruling dynasty, which over time is subject to the same weakening of power again . </P> <P> The antique concept of the architecture of a Greek polis or Roman civitas is based on a structure of main and smaller roads running through the entire city, and dividing it into quarters . The streets are oriented towards public buildings like a palace, temple, or a public square . Two main roads, (cardo and decumanus) cross each other at right angles in the center of the city . A few cities were founded during the early Islamic Umayyad Caliphate, the outlines of which were based on the Ancient Roman concept of the Ideal city . An example of a city planned according to Hellenistic concepts was excavated at Anjar in Lebanon . </P> <P> More often than founding new cities, the new Islamic rulers took over existing towns, and transformed them according to the needs of the new Islamic society . This process of transformation proved to be decisive for the development of the traditional Islamic city, or Medina . The principle of arranging buildings is known as "horizontal spread". Residencies and public buildings as well as private housing tend to be laid out separately, and are not directly related to each other architectonically . Archaeological excavations at the city of Jerash, the Gerasa of Antiquity, have revealed how the Umayyads have transformed the city plan . </P> <P> The architecture of the "oriental" - Islamic town is based on cultural and sociological concepts which differ from those of European cities . In both cultures, a distinction is made between the areas used by the rulers and their government and administration, public places of everyday common life, and the areas of private life . Whilst the structures and concepts of European towns originated from a sociological struggle to gain basic rights of freedom--or town privileges--from political or religious authorities during the Middle Ages, an Islamic town or city is fundamentally influenced by the preservation of the unity of secular and religious life throughout time . </P>

The dominant architectural structure in islam is the