joined the sedentary and urbanizing peoples of the Mediterranean rim, the Middle East, Greater India, and China into a single field of historical interaction and change. Important innovations occurring in one part of the zone tended to spread to the other parts of it through trade, military conquest, human migration, or gradual diffusion. Moreover, the intercommunicating zone “grew” over the course of time by incorporating peoples in peripheral areas — sub-Saharan Africa, Southeast Asia, Central Asia, Europe north of the Alps — into the web of interrelations. Thus, the history of Africa and Eurasia in premodern times becomes more than the stories of individual, geographically bounded nations, cultures, or empires. It is also the history of the “unconsciously inter-regional developments,” to quote Hodgson, which “converge in their effects to alter
the general disposition of the Hemisphere
.” 12
One of the most important dimensions of this “hemispheric history” was the role of pastoral populations who inhabited the great arid belt which ran diagonally from southwest to northeast across the intercommunicating zone, that is the chain of steppes and deserts extending from the Sahara through the Middle East and Central Asia to the Gobi. Contact between the herding peoples of the arid zone and sedentary societies tended in normal times to be mostly beneficial to both, involving the exchange of goods and elements of culture. However, the pastoralists, owing to their mobility and ethos of martial strength, were always a potential threat to the far richer settled civilizations. At periodic intervals beginning in the eighteenth century B.C. or earlier, nomadic invaders poured into neighboring agrarian lands, pillaging cities, terminating dynasties, and generally upsetting prevailing cultural and social patterns over wide areas of Eurasia and Africa. The last great nomadic movement occurred in the thirteenth century, when the Mongols and their Turkish-speaking allies erupted out of Central Asia and conquered China, Russia, and most of the Middle East, creating the largest territorial empire the world has ever known.
Islam had come upon the world scene in the seventh century in connection with the explosion of Arabic-speaking, horse-mounted warriors out of the Arabian desert under the leadership of theProphet Muhammad and his successors. Western historical writing has given a great deal of attention to the early evolution of Islamic civilization, that is, the “classical” age of the Abbasid Caliphate (or High Caliphate) centered on Baghdad between the eighth and tenth centuries. For this period the astonishing contributions of Muslims to world history in art, science, medicine, philosophy, and international commerce have been recognized, especially in so far as they were a major formative influence on the rise of Christian European civilization in the early Middle Ages. But precisely because historians of the West have been interested in Islam mainly in terms of its effects on the development of European institutions, the subsequent periods of Islamic history up to modern times have been given less heed. Indeed, the conventional perspective in European and American textbook writing has been that Islamic civilization reached its “peak” during the Abbasid age and thereafter went into a gradual but inexorable “decline.” This notion that Islam somehow atrophied after the tenth or eleventh century has largely turned on the Western perception (considerably exaggerated) that Muslims rejected the intellectual heritage of Hellenistic rationalism about the same time that Europeans “rediscovered” it. Consequently, so the argument runs, the West, having adopted a “scientific” and “rational” view of the natural world, was able to “progress” in the direction of world dominance, while “traditional” civilizations such as Islam languished and fell further and further behind.
In fact, the period of