The Great Wall of Gorgan is a Sasanian-era defense system located near modern Gorgan in the Golestān Province of northeastern Iran, at the southeastern corner of the Caspian Sea.
The wall is located at a geographic narrowing between the Caspian Sea and the mountains of northeastern Iran. It is one of several Caspian Gates at the eastern part of a region known in antiquity as Hyrcania, on the nomadic route from the Eurasian Steppe to the Iranian heartland. The wall is believed to have protected the Sasanian Empire to the south from the foreign peoples of the north, probably the White Huns. The wall is described as "amongst the most ambitious and sophisticated frontier walls" ever built in the world and the most important of the Sasanian defense fortifications.
It is long and wide and features over 30 fortresses spaced at intervals of between . It is surpassed only by the wall systems of the Great Wall of China and Cheolli Jangseong (in modern-day North Korea) as the longest single-segment building and the longest defensive wall in existence.
Names
Among archaeologists, the wall is also known as "the Red Snake" (Turkmen: Qizil Alan), due to the colour of its bricks. In Persian, it was known as "Alexander's Barrier" ( Sadd-i-Iskandar) or "Alexander's Wall", as Alexander the Great is thought by early Muslims to have passed through the Caspian Gates on his hasty march to Hyrcania and the east. It is also known as "Anushirvân's Barrier" ( Sadd-i Anushiravan) and "Firuz/Piruz's Barrier" () and is officially referred to as the "Gorgan Defence Wall" ().
Description
The barrier consists of a wall long and wide,
The archeologist M. Y. Kiani, who led the research team in 1971, believed that the wall was built during the Parthian Empire (247 BC–224 AD) and that it was reconstructed and restored during the Sassanid era (3rd–7th century AD). OSL and radiocarbon dating indicated a date for both walls in the late 5th or 6th century AD.