These were the homeland of the twin Dwarf kingdoms of Belegost and Nogrod. However, after the end of the First Age of the Sun, when the Elf and Dwarf kingdoms of Beleriand were destroyed, all but a small part of the Blue Mountains sank into the sea. Even that part who remained above the sea was cleft in two by the Gulf of Lune. Here the master of the Falathrim Elves of Beleriand, Lord Círdan, built the Grey Havens, the last harbour of the Eldar upon Middle-earth. And on that small remaining piece of Beleriand west of the Blue Mountains, called Lindon, was the kingdom of Gil-galad, the last High-King of the Eldar on Middle-earth. Right through the Third Age, Lindon survived as an Elf land and the Blue Mountains remained a homeland and refuge for several Dwarvish peoples.