At the point of the connection of the wall and the drainage canal from the dam, architects discovered the remains of the Great Wall of Gorgan.

Excavations on the eastern side of the Caspian Sea, opposite to Derbent, revealed the Great Wall of Gorgan, the eastern counterpart to the wall and fortifications of Derbent.

The Great Wall of Gorgan was built during the Parthian dynasty simultaneously with the construction of the Great Wall of China and it was restored during the Sassanid era (3-7th century)

The Great Wall of Gorgan is a series of ancient defensive fortifications located near Gorgan in the Golestān Province of northeastern Iran, at the southeastern part of the Caspian Sea.

The Alexander romance identified the Gates of Alexander, variously, with the Pass of Dariel, the Pass of Derbent, the Great Wall of Gorgan and even the Great Wall of China.

An alternative theory links it to the so-called "Alexander's Wall" (the Great Wall of Gorgan) on the south-eastern shore of the Caspian Sea, 180 km of which is still preserved today, albeit in a very poor state of repair.

On the border to Khurasan Iranian Sassanides a strong wall, named the "Great Wall of Gorgan" or the "Red snake", was built to protect Iran from invasions of so-called White Huns - Khionites (X'iiaona and Xyôn in Zoroastrian Texts).

As this empire stretched from Turkey in the west, where a similar wall is constructed near the Caspian Sea called The Great Wall of Gorgan, which is 155 km in length and to the east up to River Indus in Sindh, where this majestic fort is located.

In ancient times savage hordes from the north invaded and ravaged southern lands through these passes and the Persian rulers who were fearful of them had to build a strong wall, 50 miles long, 29 feet high and 10 feet wide, for fortification purposes, ruins of which can still be seen (e.g. Great Wall of Gorgan).