In reality, both structures were built by Persian monarchs. Derbent (in Persian دربند Darband, meaning "closed gates"), was established in the end of the 5th or the beginning of the 6th century, when the city was refounded by Kavadh I of the Sassanid dynasty of Persia. 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)[2]