The Iron Gates of the Baba-tag Mountains in Sogdiana
At the founding of the Kushan empire in the first century AD, a long corridor of territory was seized between Bactria-Tokharistan and the middle course of the Amu Darya. This created a Kushan barrier along the entire southern and western Sogdian border, seemingly to isolate Sogdiana - deliberately or otherwise.
A Kushan fortification wall which shut the Iron Gates (shown here), a narrow but popular linking route between Sogdiana and Bactria in the Baba-tag Mountains (close to modern Derbent), would suggest that the barrier was deliberate.
In the Middle Ages, the pass occupied an important strategic position as it was used by numerous trade caravans and bodies of troops. It was the shortest way of getting from Bukhara, Samarkand, and Chach (Shash) to Bactria and India, and back from India and Bactria to the Central Asian cities to the north.
In 630, Xuanzang described in his notes the gorge as a defensive passage that was covered with iron and was locked with a double-leaf gate. The famous Arab geographer, Al-Yaqoubi, tells about a ninth-century city in Sughd and also mentions this passage. Another Chinese chronicle tells of a city, a temple, and an iron gate that gained its name due to its colour and iron.