The Great Wall of Gorgan (Fig. l), also known as Sadd-i Iskandar (" Alexander's Barrier"), Sadd-i Piruz (" Barrier of Peroz"), Sadd-i Anushiravan (" Barrier of Khusrau") and Qizil-Alan (" the Red Snake"), is at least 195 km. long, including a c. 3 km. long gap, where the Pishkamar Rocks made an artificial boundary unnecessary (Figs. 2, 5; Nokandeh and Omrani Rekavandi 2003; cf. Charlesworth 1987; Talbert 2000: maps 96-97). It is, to our knowledge, the longest ancient barrier between the Hungarian Plain (Napoli 1997: 291-310; Kolnik 1999) and China. The Great Wall of China (in fact not a single wall), made of, or faced with, stones or bricks, dates largely to the early post-medieval period and not, as commonly thought, to the 3rd century BC (Waldron 1990). The ancient predecessors of the Great Wall of China did not use ashlar or bricks, but locally available raw materials, such as earth, unworked stone and tamarisk wood (Lindesay 2003: 52-53, pl. 3, cf. 23, pl. 6; Lovell2006: 42, 56-57, 71, 82; Stein 1912: 63, figs. 163, 165; Waldron 1990: 13-47). While some of these linear barriers were longer and remarkably sophisticated in signal transmission and in taking advantage of the terrain (Di Cosmo 2002: 141, 145-46; Lovell 2006: 24, 42-43, 46, 83, 91-92), they were of more basic and less durable construction. The scale of the Wall of Gorgan compares also favourably with that of the most elaborate ancient barriers in Europe. It is longer than its two famous British counterparts, the stone-built Hadrian's Wall and the Antonine Wall (an earthwork) taken together; only the 548 km.-long German" Limes" reaches a greater length than the Gorgan Wall. It is worth noting that the German" Limes" consisted in its most developed form of a rampart, ditch and palisade in the province of Germania Superior and a thin wall, presumably without walkway, in Raetia. The wall in Raetia was some 166 km. long (Braun

1984: 5). Thus, if we exclude earthworks, it appears that the Gorgan Wall may have been the longest wall anywhere in the ancient world. The German" Limes", lacking insurmountable obstacles and its course paying little attention to the terrain, was designed as a line of control rather than an impenetrable defensive system. The Wall of Gorgan, by contrast, was wide enough (even its width appears to have been in most sections around 2 m., rather than the maximum observed 10 m.) to carry a walkway and was presumably a significantly more substantial obstacle. It is lined by a chain of forts, which, unlike the German" Limes" and like Hadrian's Wall, abut the wall. 36 such military compounds, including three recently discovered along the eastern section of the wall (Nokandeh and Ornrani Rekavandi 2003), have been identified along the wall. They range in size from c. 1.4 to 7.2 ha., not counting three small compounds, possible fortlets, of c. 0.03 to 0.12 ha. size (Nokandeh and Ornrani Rekavandi 2003). This suggests that this massive linear barrier was designed to be manned by a substantial standing army.