What do the geographical areas included in this volume have in common over a period reaching from the fifth/eleventh to the twelfth/eighteenth century that would give meaning to both the periodisation and the geographical subdivisions used here? As noted in their introduction by the editors of volume 3 of the New Cambridge history of Islam (The eastern Islamic world, fifth/eleventh to twelfth/eighteenth centuries), a certain degree of arbitrariness always accompanies the need to make temporal and territorial divisions. The obvious Mediterranean articulation of the political and commercial trends dealt with in this volume should not obscure the deep connections that linked the western and eastern Islamic worlds – their populations, their religious and political concepts and practices, and their economies. It is also obvious that the encounter, not to say clash, with the two great civilisations of India and China mostly affected the eastern regions of the Islamic world, while the encounter and clash with Christendom had a deeper impact on the western Islamic regions. But here again things were not as simple as may appear. The westward diffusion of tea from China can be used to exemplify the often convoluted paths through which links between different areas were established. Having been used in the Chinese empire for centuries, tea was not introduced into Iran until the eleventh/seventeenth century; yet it was not from there that it crossed into the Ottoman lands.