While trying to search published material in the Internet about Dariel Pass I came across the above reference piece on Gog and Magog, and was pleasantly surprised to see the Muslim citations on the above subject, including the following passage:
"There were also further Islamic versions of the legend. The Muslim Chronicle of Tabari relates that Schahrbaraz, prince of Armenia, sent a man to seek the site of Dulcarnain's Gate; years passed, and then a ragged traveler returned . . . but the prince did not know him until he exhibited a magnificent ruby and named himself as the explorer long thought lost. He had found the Gate, and the ruby was the proof of it; the jewel had been brought to him by an eagle, which dove for it in the moat below the wall.
And another tale tells of the journey of Sallam the Interpreter, 842-844 AD, who set forth to find the Gate. Sallam crossed the Caucasus, probably through the pass of Dariel, and traveled along the northern shores of the Caspian Sea. Here he found towns in ruins, and was told they had been laid waste by the peoples of Gog and Magog. Further on, he reached a village named Yka in which Dhou'l-Karnain had once encamped with his army. Three days beyond Yka lay a wall with an iron gate, which Sallam knew for Dulcarnain's Gate because of the writing upon it. The key to the gate was a cubit and a half long, hanging from a chain eight cubits in length. (Arab historians writing of Sallam's journey explain that the wall was the Great Wall of China.)"
The Qur'an mentions a world emperor by the name of Dhul Qarnain (the King who put on a crown having two horns) in relation to the story of Gog and Magog who built the great wall to close gap between two mountains (Surah al-Kahf). While there has been much controversy as to who this personality was in the Islamic sources, some believing that he was Alexander the Greek, while others considered some other great king from Persia, the right answer about the identity is Emperor of Cyrus of Persia. He was able to combine the territories of Persia and Media for the first time and as a symbol of that unification of states, he wore that crown of two horns, and as such was known as Dhul Qarnain by the Semitic people of his time.
One of the great scholars of Islam, the late Mowlana Abul Kalam Azad, the president of Indian National Congress during the British rule, in his tafsir (explanation of the verses of the Qur'an) provide enough conclusive evidences to suggest that Dhul Qarnain was none other than Emperor Cyrus of Persia. He built a wall in the Caucasus, which today probably goes more by the name of Dariel Pass, to stop the marauding activities of Gog and Magog (a Mongoloid race).