Yajooj Majooj is one of the most common Quranic story which is narrated among elders & youngsters but it is also one of the most misunderstood Islamic story, here are the details of the story from Quran & Sunnah.
According to Quran it was in the era of Zulqarnain when he passed a valley that people complained about the people of Yajooj and Majooj. People said they spread mischief in their land so Zulqarnain decided to build a wall between them.
Quran narrates the story in the following words:
[junkie-alert style=”green”] They said: “O Dhul-Qarnain! Verily! Ya’jûj and Ma’jûj (Gog and Magog) 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?” (94) He said: “That (wealth, authority and power) in which my Lord had established me is better (than your tribute). So help me with strength (of men), I will erect between you and them a barrier. (95) “Give me pieces (blocks) 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 molten copper to pour over them.” (Surah Al-Kahf: 94-96) [/junkie-alert]
This is the wall which has stopped them from spreading mischief and trouble but before the end of the world they will reappear once again. It will be during the era of Imam Mehdi and Esa (Jesus) May Allah Bless Him.
About their coming Quran says:
And on that Day [i.e. the Day Ya’jûj and Ma’jûj (Gog and Magog) will come out], We shall leave them to surge like waves on one another, and the Trumpet will be blown, and We shall collect them (the creatures) all together. (Surah Al-Kahf: 99)
As Muslims we should know the basic details about the things and matters that are related to our religion. Rather than sharing gossips our knowledge should be based on authentic narrations.
Hudhaifah bin Usayd said, ”We were sitting in the shade of the chamber of the Prophet (sallal-laahu alayhi wasallam) discussing, and he said, what are you discussing? They said, we are talking about the Hour. He (sallal-laahu alayhi wasallam) said: The Last Hour will not come until there appear ten signs before it: the Smoke, the appearance of ad-Daj-jaal, the Beast, the rising of the sun in its place of setting, the coming forth of the descent of Eesaa the son of Maryam, the appearance of Gog and Magog, and the three Subsidences, (one in the West, one in the East, and one in the Arabian Peninsula), and at the end a fire will issue forth from the Yemen and drive the people to their place of assembly. (Abu Daawood 4/115)
The coming of Yajooj & Majooj will be after the emergence of Dajjal (Anti-Christ), it will be at a time when Muslims will be united under the leadership of Imam Mehdi & Jesus that they will emerge spreading chaos.
The exact location of the wall is not known, many scholars and researchers have made guesses and wrote books in Urdu, English, Arabic and different languages but these are mere guesses.