The Silmarillion

Thingol is King of the Grey Elves, “the fairest and the most wise and skilful of all the Elves of Middle-earth” (42). They are known as the Sindar. During the age of the Chaining of Melkor, a Sindar named Lúthien is born, the only child of Thingol and Melian. During the second age of the captivity of Melkor, the Dwarves arrive from over the Blue Mountains. They call themselves Khazâd, but the Elves call them Naugrim, the Stunted People, and Gonnhirrim, Masters of Stone. The Dwarves have carved great halls and mansions from many mountains, the greatest of which is Khazâd-dûm (also named the Dwarrowdelf or Hadhodrond) in the Misty Mountains. The Elves are amazed by the appearance of the Dwarves, who quickly learn Elvish. The relationship between the two is “cool” (42) but profitable.

Melian tells Thingol that they need to build a fortress, as evil will inevitably come to Middle-earth. They hire the Dwarves of Belegost and pay them in pearls and wisdom. They build a huge mansion named Menegroth, the Thousand Caves, decorated with images of Valinor. Many years pass, and Melian and her family are happy in their new home.

During the third age of the captivity of Melkor, however, the Dwarves “became troubled” (43).