Tafsir of Al-Kahf 18:93

حتى إذا بلغ بين السدين

Then he followed (another) way. Until, when he reached between two mountains, meaning, he traveled from the east of the earth until he reached a place between the two mountains which were next to one another with a valley in between, from which Ya'juj and Ma'juj (Gog and Magog) will emerge into the land of the Turks and spread mischief there, destroying crops and people. Ya'juj and Ma'juj are among the progeny of Adam, peace be upon him, as was recorded in the Two Sahihs;

إن الله تعالى يقول يا آدم

فيقول لبيك وسعديك

فيقول ابعث بعث النار

فيقول وما بعث النار

فيقول من كل ألف تسعماية وتسعة وتسعون إلى النار وواحد إلى الجنة

فحينيذ يشيب الصغير وتضع كل ذات حمل حملها فقال إن فيكم أمتين ما كانتا في شيء إﻻ كثرتاه يٲجوج ومٲجوج

"Allah said: "O Adam.'' Adam said, "Here I am at Your service.'' Allah said, "Send forth the group of Hellfire.'' Adam said, "What is the group of Hellfire?" Allah said: "Out of every thousand, nine hundred and ninety-nine will go to Hell and one will go to Paradise.'' At that time young men will turn grey and every pregnant female will drop her load. Among you are two nations who never come to anything but they overwhelm it with their huge numbers. (They are) Ya'juj and Ma'juj.''

وجد من دونهما قوما ﻻ يكادون يفقهون قوﻻ

he found before them a people who scarcely understood a word. he could not understand their speech, because they were so isolated from other people