The Ancient World’s largest fortresses: Persia’s northern defences in Late Antiquity

In the 4th to 6th centuries AD, Persia was under attack from the north by the ‘White Huns’ and other powerful groups of steppe warriors. Persia’s response was to create a massive fortification belt – unsurpassed in scale anywhere in the ancient and medieval world, with the only possible exception of China. Eberhard Sauer, Jebrael Nokandeh, Hamid Omrani Rekavandi, Mohammadreza Nemati, and Mehdi Mousavinia have explored the backbone of the system: the densest concentration of mega-fortresses in the late antique world, in the Gorgan and Tehran Plains of Iran.