Book excerpt: During the early medieval Islamic expansion in the seventh to eleventh centuries, al-Hind (India and its Indianized hinterland) was characterized by two organizational modes: the long-distance trade and mobile wealth of the peripheral frontier states, and the settled agriculture of the heartland. These two different types of social, economic, and political organization were successfully fused during the eleventh to thirteenth centuries, and India became the hub of world trade. During this period, the Middle East declined in importance, Central Asia was unified under the Mongols, and Islam expanded far into the Indian subcontinent. Instead of being devastated by the Mongols, who were prevented from penetrating beyond the western periphery of al-Hind by the absence of sufficient good pasture land, the agricultural plains of North India were brought under Turko-Islamic rule in a gradual manner in a conquest effected by professional armies and not accompanied by any large-scale nomadic invasions. The result of the conquest was, in short, the revitalization of the economy of settled agriculture through the dynamic impetus of forced monetization and the expansion of political dominion. Islamic conquest and trade laid the foundation for a new type of Indo-Islamic society in which the organizational forms of the frontier and of sedentary agriculture merged in a way that was uniquely successful in the late medieval world at large, setting the Indo-Islamic world apart from the Middle East and China in the same centuries. Please note that The Slave Kings and the Islamic Conquest, 11th-13th Centuries was previously published by Brill in hardback (ISBN 90 04 10236 1, still available).