The Islamic world developed its own highly sophisticated, effective and varied style of fortification. It drew upon pre-existing Romano-Byzantine, Iranian, Central Asian and Indian traditions of military architecture, plus influences from China, to produce something new and distinctive. In turn, Islamic concepts of military architecture influenced fortifications throughout the Byzantine Empire and, to an even greater extent, in Western Europe. One key point of distinction with the latter in particular was that Islamic fortifications were primarily focussed upon defending cities and frontiers, rather than being associated with royal and feudal elites, as was the case in most of Europe. Despite this highly practical role, medieval Islamic military architecture went beyond the merely functional, and the finest surviving examples are imbued with a sense of symbolic magnificence. This title, the first of several proposed volumes in the Fortress series, takes a look at early Islamic fortifications in the central and eastern lands. It covers the historical background, socio-political circumstances, and purposes of early military architecture; the incorporation of several different traditions and the development of a distinctive character; and the fortifications' role in protecting industry, trade and the frontiers of the Islamic world. Subsequent volumes will deal with the 12th to 16th centuries in the center and east, and the western Islamic lands of North Africa and the Iberian Peninsula, respectively.