The high ranges of the Caucasus in what is now Russian territory running between the Caspian Sea and the Black Sea, serve as a natural dividing wall between Europe and Asia. In this mountainous region there were certain passes through which the savage Gog and Magog (Yajuj and Majuj) tribes from the south used to enter the northern part of Iran and plunder it. Here, till today, there are signs of an ancient wall. There is every probability that this was the very wall which was constructed by Dhu’l-Qarnayn for security purposes. To erect an ‘Iron Wall’ to ward off enemies is a feat which generally generates a sense of pride in people. But even after constructing such an invincible wall, Dhu’l- Qarnayn did not lose his modesty and humility. He had set his eyes not on his own creations but on God’s mighty powers, and a human being’s power is nothing as compared to God’s might.