Then he retraced his steps and followed yet another course that enabled him to traverse (1) the routes (2) of the lands and bring their peoples into submission, setting out toward the north: “until, when he reached [the place] between the two barriers” (18:93)—meaning that he arrived at a spot located midway between the two barriers that have existed since Allah created the earth. These barriers are immense, towering chains of contiguous mountains that rise from that narrow pass, the only corridor leading to the eastern and western seas. They lie in the territory of the Turks; on this point the exegetes and historians concur.

They differ only as to which range is meant: are they the Caucasus Mountains, a range somewhat nearer in Azerbaijan, the Altai range, or the mountains that adjoin the Chinese Wall in Mongolia—which appears to be the most plausible view.

On any of these opinions, he found at the gap between those mountain chains “a people who could scarcely understand a word” (18:93) because their language was so remote and their grasp of other tongues so limited. They said, “O Dhul-Qarnayn, Gog and Magog are wreaking havoc in the land” (18:94). These are vast nations descended from Japheth son of Noah, largely of Turkic stock and others, whose circumstances and attributes are described in detail elsewhere.

They continued: “Shall we pay you a tribute so that you may erect a barrier between us and them?” (18:94). He answered, “That with which my Lord has established me—of power, means, and authority—is better; so lend me your strength, and I will build between you and them a rampart.” He did not say “a barrier,” for what was constructed was only that narrow pass—the defile—lying between the two natural barriers, that is, the chains of those mountains.