This pass was famously used by Alexander the Great in 330 B.C. during his pursuit of the Achaemenid king Darius III.
In the strictest historical sense used by Greco-Roman authors, the Caspian Gates (ancient Caspias portas ) refer to a ground-level pass through the in modern-day Iran. The Caspian Gates
Ancient writers like Pliny described it as a narrow, scorched-looking passage with salt water leaching from the rocks, a description that still matches the modern site's barren, eroded appearance. CASPIAN GATES - Encyclopaedia Iranica This pass was famously used by Alexander the Great in 330 B