What is the story of Gog and Magog with Dhul-Qarnayn as mentioned in Surat Al-Kahf?

Gog and Magog are two tribes descended from Japheth son of Noah. Their story with Dhul-Qarnayn is mentioned in the Holy Quran in Surat Al-Kahf, stating that they were corrupting the earth and that Dhul-Qarnayn built a barrier between them and another people. It is mentioned in Surat Al-Anbiya' that they will emerge when the True Promise draws near. And in Sahih Muslim, it is stated that they will emerge at the end of time and that Jesus (peace be upon him) will supplicate against them, leading to their destruction. Whatever is not mentioned about them in the Quran and Sunnah should not be a preoccupation for the Muslim.