Why was the khyber pass so important to south asia for centuries

Full AnswerThis pass was used by the Greeks, Persians, British and Afghans in military campaigns. Some of the most famous military leaders in history used the Khyber Pass as an invasion route, including Alexander the Great, Darius I of Persia, Mahmud of Ghazni and Nadir Shah.In 1839 during the First Anglo-Afghan War, the British and Afghans battled in a number of skirmishes. The Khyber Pass was left under the control of the British following the Second Anglo-Afghan War in 1879 following the signing of the Treaty of Gandamak.The Pashtun people, who consider the pass as their own land, have levied tolls on travelers going through the pass in exchange for their safety. As of 2015, the Pakistani government controls the pass, which includes a road for automobiles, a road for caravans and a railroad. The railroad opened in 1992 and includes 34 tunnels and 94 bridges connecting the towns of Jamr?d, Pakistan, with Landi Kh?na in Afghanistan.

The answer is a)advocates of divine right.