Abū Zayd ʿAbd al-Raḥmān ibn Muḥammad ibn Khaldūn — 14th-century Arab historian, statesman, and judge born in Tunis to an Andalusian family exiled after the fall of Seville, and the author of the Muqaddimah (Introduction), the prolegomenon to his universal history Kitāb al-ʿIbar (Book of Lessons). The Muqaddimah is, by the reckoning of most 20th-century social theorists who eventually encountered it — Arnold Toynbee called it "undoubtedly the greatest work of its kind that has ever yet been created by any mind in any time or place" — one of the foundational works of what later Europeans would reinvent as sociology, historiography, and political economy. It was written in 1377 during a four-year withdrawal from public life to a fortress in present-day Algeria, after twenty years of intimate and often perilous service to the fragmenting courts of North Africa and Muslim Spain.
Ibn Khaldun's central concept is ʿaṣabīyya — variously translated as group feeling, social solidarity, or corporate cohesion — the tribal or lineage bond that gives a people collective political force. His distinctive thesis is that the rise and fall of dynasties across North African history follows a predictable pattern: a rural or tribal group with strong ʿaṣabīyya conquers a settled dynasty whose original group cohesion has been dissipated by the softening effects of urban luxury; the conquerors establish themselves in cities, accumulate wealth and sophistication, and within three or four generations lose the cohesion that brought them to power, at which point a new group with fresh ʿaṣabīyya displaces them. The pattern is reinforced by a sustained account of the relation between nomadic and sedentary life, an early labor theory of value, an analysis of the division of labor, a theory of taxation and its effects on economic activity ("at the beginning of the dynasty, taxation yields a large revenue from small assessments. At the end of the dynasty, taxation yields a small revenue from large assessments"), and a comparative sociology of crafts, sciences, and religious institutions.
Ibn Khaldun was unknown to Europe until Ottoman scholars of the 17th and 18th centuries introduced the text, which reached French Orientalists in the 19th century; Weber and Durkheim, working in broadly analogous directions, appear not to have read him. His rediscovery as precursor to modern social science has been one of the ongoing intellectual projects of the 20th and 21st centuries, complicated by the reluctance of a European discipline to find its origins outside itself. Recent scholars have also cautioned against reading him too anachronistically: he was working within a sophisticated Arabic Aristotelian and Islamic theological tradition whose categories are not simply modern sociology in disguise.