Answer:
High mountains between the two cities made land travel difficult and time-consuming.
Explanation:
There is the great mountains of the Himalayas that cut in half the passage by land from Delhi to Dunhuan that´s why there was no land routs for a direct passage from Delhi to Dinhuang, having to climb the mountains or surround them was too difficult and time consuming, that´s why it was easier to go through other route to the east and the going north th Dunhuang.
