This volume is a real huge work, impressive for the amount of data dealt with. It was the outcome of five field works, 2006-2009, held by the Universities of Edinburgh and Durham, with the substantial cooperation of the Iranian authorities. This great volume is subdivided into four sections and 23 chapters; at the end of the volume there are Appendices and a comprehensive Bibliography preceding 24 colour plates and the translation into Persian of the Introduction and Summary.

The region affected by the research is the plain of Gorgān, located to the East of the Caspian Sea, representing the bulk of ancient Hyrkania. In that region a massive defence system constituted by a great wall now divided into two sections and a constellation of forts, digs, and fortified cities has been well-known to archaeologists who, however, have been unable to date them with some certainty until now. The great walls are named Gorgān Wall and Tammīsheh Wall, and are 195 and 11 km long, respectively. More than 30 forts associated with these walls were identified, some of them measuring more than 40 ha in surface. Altogether they represent the largest military installation known from Antiquity. Scope of these impressive defensive structures was the protection of the economic bulk of the Sasanian Empire from the nomadic populations of the Eurasian steppes. Also a Sasanian city, Dasht Qal'eh, and a prehistoric site, Qelīch Qōīneq, were affected by this research work (Sect. B chaps. 13 and 14).

Section A (Introduction and History of Research) presents us with an extensive description of the history of research: notwithstanding the evident importance of these archaeological sites, modern research has been unable to identify either the date or the exact structure of these fortifications up to now. The chronology of the walls fluctuated between the Hellenistic and the Early Islamic ages (really impressive is Table 2:1 with all the different hypotheses about the dates regarding the walls, in both ancient and modern sources)! The foremost result of this archaeological mission is that it allowed to anchor this defensive structure firmly to the years between the mid-fifth century AD, with a life span of little more than two centuries.

Section B: Field Research is by far the longest section of this book (24-418). It is subdivided into 11 chapters. Extensive analyses of the construction stuffs (backed bricks) and architectural features are fully analyzed in four chapters: two dedicated to the Gorgān Wall (chaps. 4 and 5) and two to the Tammīsheh Wall (chaps. 7 and 8). The analysis of the kilns is conducted on some exemplars among hundreds individuated in the area during the extensive preliminary surveys. The architectural study demonstrated that the two Walls, now separated by the south-eastern corner of the Caspian Sea, were originally branches of one and the same structure, maybe physically connected with each other, surely parts of the same strategic plan. A section of the wall then ended up under water due to the Derbent Regression that modified the level of the sea (35-37). Also the forts along both the Gorgān and the Tammīsheh Walls were explored selectively (over 30 forts along the Gorgān Wall, 1, perhaps 2 along the Tammīsheh Wall). The forts share much of their characteristics with military structures known elsewhere in the Near East, especially in Upper Mesopotamia, such as Tell Bâti, Tell Brak or Ain Sinu. The latter were traditionally attributed to the Roman army, but now the astonishing similarities with those of the Gorgān Wall compel to a reconsideration of the question anew (234-9). A large section is devoted to the study of different military structures (named 'Sasanian campaign bases') with a huge amount of comparative materials from the entire Sasanian Empire (Chap. 12, 303-81).

Section C: Specialist contributions deal with Underwater Survey of the Tammīsheh and Gorgān Walls; Archaeomagnetic Studies of Features Along the Gorgān and Tammīsheh Walls; OSL Dating; Sasanian Ceramics from the Gorgān Wall and Other Sites on the Gorgān Plain; Vessel Glass and Beads; Animal Bones; Charcoal; Bitumen. Section D: Conclusion, ends the volume.

The epochal importance of this work cannot be overlooked. Such an in-depth analysis should deserve an extensive review-article. The core of this work is centered on the economy and on the army (both the scale of the army and the military structures and organization) of the Sasanian Empire. The data, provided for the first time here, reveal how impressionistic and fundamentally wrong many opinions widely shared about these subjects were. As far as the economy is concerned, the landscape archaeology and the excavations conducted in two urban centers provide information about a densely populated rich area, producing agricultural surplus allowing the development of urban conglomerations more than a millennium before the building up of the Wall (city of Qelīch Qōīneq, chap. 14). The stratified excavations of some settlements in this area produced also some large hydraulic work, dating back to the Parthian age.

The main concern of the authors was about linear defenses and military structures in Late Antiquity on a strongly comparative basis with what happened more or less contemporaneously in the West (Roman Empire) and in the East (China). Notwithstanding the difference in scale, the Sasanian walls were the grandest fortification structure built with burnt bricks in Late Antiquity. The Romans ones in Germany were only in earthwork, while the Great Wall acquired its present aspect only during the Modern Age. Neither in Britain, nor in Germany and in China were any comparable military structures near the walls found. The Iranian structure is by far the most complex and articulated linear defense known until now.

The radiocarbon provides data with a relative precision, so we are sure now that "no part of either wall was built before the mid AD 420s at the very earliest ... and that all of the Gorgān wall was completed by the AD 540s at the very latest" (594). This fact compels to be speculative about the precise circumstances that induced the Sasanian power to embark on such an enterprise, but, if the hypothesis of the authors is correct, the authorship of the plan is due to Peroz (AD 457-484), while about the date of the disposal of the Wall it is impossible to settle if it happened on the occasion of an invasion by the Turks in AD 614-7 or with the Islamic invasion in 630s, or some other event in 650s.

This book is highly recommended to scholars engaged with the economy and the military history of Sasanian Iran, with landscape archaeology, water management, comparative Eurasian history and theory of Empires.

Tommaso Gnoli