There, in that locale and those surrounding lands, he encountered a people that included both Muslims and unbelievers, the upright and the depraved. This is indicated by the divine words: “We said, ‘O Dhul-Qarnayn, either you punish them or treat them with kindness’” (18:86).
• The speaker addressing him may have been a prophet of Allah or one of the scholars.
• Or the sense is that, by virtue of the power granted to him, he was providentially given the choice.

Otherwise, it is self-evident that the Sacred Law never equates the two divergent courses of beneficence and wrongdoing.

So he declared: “As for the one who has done wrong, we shall punish him; then he will be returned to his Lord, who will punish him with a punishment most severe (18:87). But whoever believes and acts righteously—his reward shall be the finest, and we shall address him with words of ease (18:88).”

This testifies to his justice, to the fact that he was a righteous king, and to the soundness of his governance.

“Then he followed a [further] course” (18:89)—meaning that, after subjugating the people of the West, he made use of the means he had been given, returning to open the land region by region until he reached the place of sunrise in the territories of China and the shores of the Pacific Ocean, the furthest point any conqueror has attained.

“There he found it rising upon a people for whom We had provided no shelter from it” (18:90): they had no covering against the sun—no woven garments to wear and no houses to enter. He discovered these inhabitants of the extreme East in just such a primitive, untamed state, like wild beasts that seek refuge in forests, caves, and underground burrows (1), cut off from the rest of mankind. At that time they were exactly as God describes them, and the lesson is that he reached a place no one else had ever reached.