Surah 18. Al-Kahf, Ayah 93

This is generally assumed to be the Caucasus. However, since neither the Qur'an nor any authentic Tradition says anything about the location of these "two mountain-barriers" or the people who lived there, we can safely dismiss all the speculations advanced by the commentators on this score as irrelevant, the more so as the story of Dhu 'I-Qarnayn aims at no more than the illustration of certain ethical principles in a parabolic manner.

Cf. xxi. 96.

It does not mean that they had no speech. It means that they did not understand the speech of the Conqueror. But they had parleys with him (through interpreters), as is evident from the verses following (xviii. 94-98).