A philosopher who applied the principles of philosophy to the study of history and sought the universal laws operating behind the flux of events. Ibn Khaldun's most celebrated work is the Muqad ma e Ibn Khuldon and Tarikh Ibn Khuldon, which was a history of the Arabs, the Iranians and the Berbers. He was the greatest historical philosopher Islam produced - a pioneer of the scientific study of history and the real founder of the science of sociology. Ibn Khaldun watched one dynasty after another fail in the Maghrib and plague destroyed whole communities. Nomadic tribes had migrated from Egypt into North Africa, causing massive devastation and a corresponding decline in traditional Berber society. Ibn Khaldun had himself emigrated to Tunisia from Spain, where the Christians had conducted a successful conquest of Muslim territory, taking Cordova in 1236 and Seville in 1248. All that was left of Muslim kingdom was the city-state of Granada and that was too was lost in 1492. Ibn Khaldun reflected on Islam that was in crisis, 'it is as if the whole creation had changed and all the world had been transformed, as if there were a new creation, a rebirth, a world brought into existence anew.' Ibn Khaldun wanted to discover the underlying causes of this change. He was to apply the principles of philosophic rationalism to the study of history, hitherto considered to be beneath the notice of a philosopher, because it dealt only with transient, fleeting events instead of eternal truths. Ibn Khaldun believed that beneath the flux of historical incidents, universal laws governed the fortunes of society. That it was a strong sense of group solidarity (asibiyyah) that enabled a people to survive and, if conditions were right, to subjugate others. This conquest meant that the dominant group could absorb the resources of the subject people, develop a culture and a complex urban life. When the ruling class became accustomed to a luxurious lifestyle, complacency set in and they began to lose their vigour. They no longer took sufficient heed of their subjects, there was jealousy and infighting, and the economy would begin to decline. Thus the state became vulnerable to a new tribal or nomadic group, which was in the first flush of its own asibiyyah, and the whole cycle began again. When complacency had set in and the stage was now set for other dominant groups to take control. Ibn Khaldun was born Abdur Rehman bin Muhammad al-Hazrami al-Ishbili Waliuddin Abu Zaid in Tunis but lived mostly in Granada and Egypt. His father was a native of Berber, but his mother was from the Arabian province Hazramat and made her son adopt the surname al-Hazrami.