Sasanian defense lines located on terrain feature Caucasus
Darial Gorge
Darial Gorge (Middle Persian: ʾlʾnʾn BBA Arrānān dar, Parthian: ʾlʾnnTROA; 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.