Allah tells us that Dhul-Qarnayn then traveled from the west of the earth towards the east. Every time he passed a nation, he subjugated the people and called them to Allah. If they obeyed him, all well and good, otherwise he would humiliate them and take their wealth and possessions. From every nation he took what his armies needed to fight the next nation. When he reached the place where the sun rises, as Allah says,

﴿وَجَدَهَا تَطْلُعُ عَلَى قَوْمٍ﴾

(he found it rising on a people) meaning a nation,

﴿لَّمْ نَجْعَل لَّهُمْ مِّن دُونِهَا سِتْراً﴾

(for whom We (Allah) had provided no shelter against the sun.) meaning, they had no buildings or trees to cover them and shade them from the heat of the sun. Qatadah said, "It was mentioned to us that they were in a land where nothing grew, so when the sun rose they would go into tunnels until it had passed its zenith, then they would come out to go about their daily lives and earn themselves a living.''

﴿كَذَلِكَ وَقَدْ أَحَطْنَا بِمَا لَدَيْهِ خُبْراً ﴾

(So (it was)! And We knew all about him.) Mujahid and As-Suddi said, "This means that Allah knew everything about him and his army, and nothing was hidden from Him, even though they came from so many different nations and lands. For,

﴿لاَ يَخْفَى عَلَيْهِ شَىْءٌ فِي الاٌّرْضِ وَلاَ فِى السَّمَآءِ﴾

(Truly, nothing is hidden from Allah, in the earth or in the heaven.)﴿3:5﴾''

﴿ثُمَّ أَتْبَعَ سَبَباً حَتَّى إِذَا بَلَغَ بَيْنَ السَّدَّيْنِ وَجَدَ مِن دُونِهِمَا قَوْماً لاَّ يَكَادُونَ يَفْقَهُونَ قَوْلاً قَالُواْ يذَا الْقَرْنَيْنِ إِنَّ يَأْجُوجَ وَمَأْجُوجَ مُفْسِدُونَ فِى الاٌّرْضِ فَهَلْ نَجْعَلُ لَكَ خَرْجاً عَلَى أَن تَجْعَلَ بَيْنَنَا وَبَيْنَهُمْ سَدًّا قَالَ مَا مَكَّنِّى فِيهِ رَبِّى خَيْرٌ فَأَعِينُونِى بِقُوَّةٍ أَجْعَلْ بَيْنَكُمْ وَبَيْنَهُمْ رَدْمًا ءَاتُونِى زُبَرَ الْحَدِيدِ حَتَّى إِذَا سَاوَى بَيْنَ الصَّدَفَيْنِ قَالَ انفُخُواْ حَتَّى إِذَا جَعَلَهُ نَاراً قَالَ آتُونِى أُفْرِغْ عَلَيْهِ قِطْراً ﴾

(92. Then he followed (another) way,) (93. Until, when he reached between two mountains, he found before them a people who scarcely understood a word.) (94. They said: "O Dhul-Qarnayn! Verily, Ya'juj and Ma'juj are doing great mischief in the land. Shall we then pay you a tribute in order that you might erect a barrier between us and them'') (95. He said: "That in which my Lord had established me is better. So help me with strength, I will erect between you and them a barrier.'') (96. "Give me Zubar of iron;'' then, when he had filled up the gap between the two mountain-cliffs, he said: "Blow;'' then when he had made them (red as) fire, he said: "Bring me Qitran to pour over them.'')