IN 1199 the Almohad empire stood at the height of its power and extent from the Gulf of Syrtis in Libya to the Tagus in Spain and the Sous in Morocco. Despite its possession of al-Andalus or Muslim Spain, still the richest and most cultivated province of the Muslim west, it was essentially a North African empire, whose great achievement had been to complete the unification of North Africa by Islam. While the Romans had divided the bloc of the Atlas to the north of the Sahara by a frontier which separated the civilisation within from the barbarism without, the Almohads had joined the two halves together in a single whole. They had done so, moreover, from a base at Marrakesh in the far south-west, at the opposite extreme from the old centre of civilisation at Carthage-Tunis in the far north-east, in other words, in the lands beyond the Roman pale. That was because they had drawn their forces, not from the civilised peoples of old Roman North Africa, but from the barbarous tribesmen whom the Romans had endeavoured to exclude. They had, in other words, succeeded where the Romans had failed, in seizing upon Berber tribalism, the common denominator of native society throughout the region, and using it for the purpose of the dominant civilisation.

Their success went back to the days of the Arab conquest at the end of the seventh and beginning of the eighth century, but more especially to the formative years of the ninth, when Islam as a creed, a way of life and a civilisation finally took shape in the Mashriq, the Muslim east, as well as in the Maghrib, the Muslim west. Such success derived from the appeal of the zealous Muslim preacher to the tribal population which surrounded the islands of urbanity formed by the Islamic cities, and it rested on a paradox, the willingness of such ‘stateless’ tribal peoples to submit to the dictatorship of such a prophet for the sake of God.