Explanation:

.The Khyber pass was the most frequently visited by the external invaders.Well-known invasions of the area have been predominantly through the Khyber Pass, such as the invasions by Cyrus, Darius I, Genghis Khan and later Mongols such as Duwa, Qutlugh Khwaja and Kebek. Prior to the Kushan era, the Khyber Pass was not a widely used trade route.