In this study of one of the fundamental institutions of the Islamic empire in the Middle East, Silverstein surveys the history of the barīd, or state postal and intelligence network, of the Umayyad and Abbasid caliphates and its various manifestations under subsequent successor states down to the Mamluk period. He also compares the barīd with the Mongol post, the yām, which included what was “perhaps the longest postal route in pre-modern history”, linking Europe and the Far East. This is institutional history in the longue durée, synthesising for the first time much material previously confined to scholarship with narrower geographical and chronological parameters, as well as breaking entirely new ground, particularly on the pre-Islamic Arabian and early caliphal barīd. This long view brings out the great importance of communications to the Arabian and Mongol nomad empires of the pre-modern Middle East, and the extent to which the interaction of their respective nomadic cultures with the institutions of settled empire led to the development of astonishingly swift communications networks.

For Silverstein, Islamic history in the proper perspective must begin long before Islam, in the pre-Islamic world of the Roman and Iranian empires, as well as in the Arabian Peninsula itself. Part I of three begins with the Achaemenids (539–330 BCE) and follows the history of the Iranian postal systems until Sasanian times (224–650 CE) before turning to the Roman cursus publicus, beginning in the reign of Augustus (23 BCE–14 CE). Silverstein argues that, although other terms for a courier or messenger (bashīr, rasūl) were also in use in sixth and seventh-century pre-Islamic Arabia, the term barīd had entered Arabic before Islam from the Greek beredarion (Latin, veredarius), and that Arabians were also familiar with the language of the Persian communications network. However, it was only with the conquest of their empire in the seventh century that the Arabians came to require a highly centralised ‘inter-regional’ postal system. This combined features of Roman, Iranian and Arabian practice and came to be known exclusively as the barīd.

Part II is the longest section of the book. It addresses the evolution and decline of the ‘caliphal barīd’ of the Umayyad and Abbasid caliphates and the postal systems of the various successor states that ruled the Islamic Middle East before the coming of the Mongols (ie c. 660 – c. 1250 ce). Three main turning-points in the history of the caliphal barīd are noted: its reorganisation and development under the Marwanid Umayyads (r. 684–750 ce); the centralisation of the postal network under the Abbasid caliph, al-Mutawakkil (r. 847–61), when, Silverstein argues, a central dīwān al-barīd (‘office of the post’) was created for the first time; finally, the disintegration of the unified caliphate during and after the late ninth century. This fragmentation of political authority necessitates the separate treatment of the communications networks of the Fatimid caliphate, the Samanid and Ghaznavid emirates and the Buyid and Seljuk states (the Seljuks, Silverstein notes, did without a formal intelligence and communications network, to their detriment).

Part III covers the much shorter period from c. 1250 – c. 1400 ce, and focuses on the Mongol yām and the barīd of Mamluk state that resisted them. Regarding the yām, Silverstein follows previous scholarship in suggesting that it was heavily influenced by the Chinese Yi (or Li). (Although he does point out that eighth-century documentary evidence suggests that the use of the term yām in Central Asia long-predated the Mongol conquests). He notes that the fully-developed yām probably influenced the communications networks of the Delhi Sultanate, the Ottomans and the Timurids. However, he makes a much fuller examination of the Mamluk barīd, another postal system said to have been modelled on the yām, and observes that the claim of the Mamluk-era writer, ‘Umarī, that the Mamluk barīd was a revived Abbasid institution (and so not simply an imitation of Mongol practice) was not entirely without foundation.

The book ends with a useful appendix on the speed of the postal systems, preceded by four conclusions. First, an efficient postal network contributed both to the material power of the monarch and his symbolic power; it was widely held that neglect of the barīd led to the fall of the Umayyads and the Seljuks' failure to confront the Isma'īlīs and Crusaders effectively. Second, the precise form of the postal system could vary quite widely between dynasties (sometimes, it seems, for symbolic and political reasons) and according to the exigencies of terrain and resources (beacons, runners, pigeons and merchants were all alternatives to riders on various mounts). Third, what was most ‘Islamic’ about ‘Islamic’ postal systems was the light burden placed on local populations thanks to centralised funding (at least in the middle Abbasid period, under the Mamluks and after the conversion of the Mongols). Finally, as noted above, nomad conquerors were in a position to exploit and enhance the communications networks of the settled regions they occupied – a distinctive feature of Middle Eastern history. Most of this makes very good use of the book's long view and is persuasive. However, the notion of an ‘Islamic’ character for postal systems perhaps requires some further justification. The argument appears to be one about acceptable forms of taxation in Abbasid and post-Abbasid, ‘classical’ Islam, but one suspects that, like the Ghaznavids, many pre-modern Islamic regimes which had less centralised and monetised tax systems imposed more heavily on local populations.

With respect to the book as a whole, it might be suggested that the tenth–twelfth centuries and the successor states to the Mongols of the fourteenth century are a little short-changed because the book's focus tends to be on the major imperial powers of the pre-modern Islamic Middle East. Also, very occasionally, the literary sources seem to be taken too much at face value. For example, in Part I, one suspects that Procopius' unfavourable comparison in his Secret History of the poor quality of Roman intelligence, under Justinian, with the reliable intelligence of the Iranians, under Khusro, is part of Procopius' wider programme of invective against the Roman emperor, and thus not secure evidence for the Justinianic post. (What it is, is further evidence for the importance of the post in the image of Near Eastern monarchy). Likewise, one wonders about the Seljuks and their lack of barīd (which, it must be said, is very widely-accepted): the Seljuks came from a pastoral nomad background and would have had natural aptitude for fast communication; might Niẓām al-Mulk's criticism of the lack of spies (aṣḥāb al-akhbār) employed by the state not be the whole story? Elsewhere, Middle Eastern influence on the Mongol yām is noted: might this have come via the remnants of Seljuk systems rather than from the Mamluks?

Overall, however, there is very little to disagree with here and much that is impressive. As the first comprehensive survey of Islamic postal networks, Silverstein's book is likely to remain a very useful reference work for some time to come. A great range of source material, in many languages, and from many regions and periods, is sifted and analysed. The balance between the literary evidence of histories, geographies and administrative manuals and the documentary evidence of papyri and other primary material is struck very well. In at least one case, a very new source is brought to bear on the question of the postal system (the anonymous, Buyid-era, Siyāsat al-mulūk, first discussed by Silverstein in 2002–3), as are many under-exploited ones (including the documentary material). In its long perspective (in total, nearly 2,000 years), and its willingness to connect institutional history to other historical patterns, including those determined by ecology and technology, this book is an important and wide-ranging contribution to Middle Eastern history. Furthermore, it is lucid, readable and elegantly produced, with clear maps and a good index.