Sasanian defense lines

The rivers Euphrates, Great Zab, and Little Zab acted as natural defenses for Mesopotamia (Asoristan). Sasanian development of irrigation systems in Mesopotamia further acted as water defense lines, notably the criss-crossing trunk canals in Khuzestan and the northern extension of the Nahrawan Canal, known as the Cut of Khusrau, which made the Sasanian capital Ctesiphon virtually impregnable in the late Sasanian period. In the early period of the Sasanian Empire, a number of buffer states existed between Persia and the Roman Empire, which played a major role in Roman-Persian relations. Both empires gradually absorbed these states, and replaced them by an organized defense system run by the central government and based on a line of fortifications (the limes) and the fortified frontier cities, such as Dara, Nisibis (Nusaybin), Amida, Singara, Hatra, Edessa, Bezabde, Circesium, Rhesaina (Theodosiopolis), Sergiopolis (Resafa), Callinicum (Raqqa), Dura-Europos, Zenobia (Halabiye), Sura, Theodosiopolis (Erzurum), Sisauranon, etc. According to R. N. Frye, the expansion of the Persian defensive system by Shapur II () was probably in imitation of Diocletian's construction of the limes of the Syrian and Mesopotamian frontiers of the Roman Empire over the previous decades. The defense line was in the edge of the cultivated land facing the Syrian Desert. Along the Euphrates (in Arbayistan), there was a series of heavily fortified cities as a line of defence. Wall of the Arabs During the early years of Shapur II (), nomadic Arabian tribesmen made incursions into Persia from the south. After his successful campaign in Arabia (325) and having secured the coasts around Persian Gulf, Shapur II established a defensive system in southern Mesopotamia to prevent raids via land. consisted of a large moat, probably also with an actual wall on the Persian side, with watchtowers and a network of fortifications, at the edge of the Arabian Desert, located between modern-day Basra and the Persian Gulf. The defense line ran from Hit to Basra, on the margin of fertile lands west of Euphrates. It included small forts at key spots, acting as outliers for larger fortifications, some of which have been uncovered. ==In the Caucasus==

Massive fortification activity was conducted in the Caucasus during the reign of Kavad I () and later his son Khosrow I (), in response to the pressure by people in the north, such as the Alans. Key components of this defensive system were the strategic passes Darial in the Central Caucasus and Derbent just west of the Caspian Sea, the only two practicable crossing of the Caucasus ridge through which the land traffic between the Eurasian Steppe and the Middle East was conducted. A formal system of rulership was also created in the region by Khusrow I, and the fortifications were assigned to local rulers. This is reflected in titles like "Sharvān-shāh" ("King of Shirvan"), "Tabarsarān-shāh", "Alān-shāh/Arrānshāh", Derbent was also the seat of a Sasanian marzban. The lines were constructed using a combination of mud brick, stone blocks, and baked bricks. The construction was carried out in three phases, extending to the end of the reign of Khusrow I, but was never actually completed. The defensive line is about 60 km in length, from the Caspian Sea to the foot of Mount Babadagh. In 1980, the Ghilghilchay wall was excavated by an expedition of Azeri archaeologists from the Institute of History of Azerbaijan. Not far from the Gilgilchay wall is the Shabran wall, located near Shabaran village. Darial Gorge Darial Gorge ( Arrānān dar, ; meaning "Gate of the Alans"), located in the Caucasus, fell into Sasanian hands in 252/253 as the Sasanian Empire conquered and annexed Iberia. It was fortified by both Romans and Persians. The fortification was known as Gate of the Alans, Iberian Gates, and the Caucasian Gates. File:The boy travellers in the Russian empire- adventures of two youths in a journey in European and Asiatic Russia, with accounts of a tour across Siberia.. (1886) (14764201711).jpg|The Darial Gorge File:The pass of Dariel (Travels in the Trans Caucasian provinces).jpg|Darial Gorge, 1847 File:დარიალის ხეობა.JPG|Darial Gorge, before 1919 ==South-east Caspian==

For the defense of the Central Asian border, a different strategy was needed: the maximum concentration of forces in large strongholds, with Marv as the outer bulwark, backed by Nishapur. Great Wall of Gorgan The Great Wall of Gorgan (or simply the Gorgan Wall) was located in north of the Gorgan River in Hyrcania, at a geographic narrowing between the Caspian Sea and the mountains of northeastern Persia. It is widely attributed to Khosrow I, though it may date back to the Parthian period. It was on the nomadic route from the northern steppes to the Gorgan Plain and the Persian heartland, probably protecting the empire from the peoples to the north, in particular, the Hephthalites. The grasslands of the Gorgan Plain was one of the wealthiest parts of the empire and a major recruiting ground for the Sasanian cavalry. The defensive line was long and wide, featuring over 30 fortresses spaced at intervals of between . It is described as "amongst the most ambitious and sophisticated frontier walls" ever built in the world, Wall of Tammisha The Wall of Tammisha (also Tammishe), with a length of around 11 km, stretched from the Gorgan Bay to the Alborz mountains, in particular, the ruined town of Tammisha at the foot of the mountains. There is another fortified wall 22 km to the west running parallel to the mentioned wall, between modern cities of Bandar-e Gaz and Behshahr. The Wall of Tammisha is considered to be the second line of defence after the Gorgan Wall. ==Other defense lines==

• the limes of Sistan ==Interpretation==

Recently, Touraj Daryaee has suggested the defensive walls may have had symbolic, ideological and psychological dimension as well, connecting the practice of enclosing the Iranian (ēr) lands against non-Iranian (anēr) barbarians to the cultural elements and ideas present among Iranians since ancient times, such as the idea of walled paradise gardens. ==See also==