ALLAH ,mention dhulqarnayn in surah al-kahaf verses (94 to 98) they say that when help was sought from him against ya’juj and ma’juj he built a barrier of iron and molten brass thus, they were unable to pierce it or scale it. But when allah’s promise is due, they will demolish it.
Dhulqarnayn was a pious and good-fearing man allah had given him strength and authority he judged people justly and helipad the oppressed and punished the oppressors he propagated religion in the east and the weat.
Once a people who were tormented by ya’juj andma’juj sought his help. They used to attack them and snatch everything they could lay their hands on so, dhulqarnayn helipad by building a strong barrier but did not take any payment from them, doing it only for alla’s sake. He only asked them for laborers to build the wall. He build it in the pass between two huge mountains because the ya’juj and ma’juj came through this pass to kill and plunder.
Thereafter, ya’juj and ma’juj could not trespass try as they may. Thus, these oppressed people were safe and happy.
Dhulqarnayn told them that the barrier will remain as long asa allah willed where after it would collapse.