After the Valar entered the world and brought order to the seas and the lands and the mountains, and subdued the fires of Melkor, there was a need for light. Aulë at the prayer of Yavanna forged two mighty lamps, Illuin and Ormal. Varda filled the lamps with light and Manwë hallowed them, and the Valar set them up on high pillars, Illuin in the furthest north upon the pillar of Helcar, Ormal in the deepest south upon the pillar of Ringol. In the middle of Arda, where the light of the lamps mingled, amid the Great Lake lay the Isle of Almaren, where the Valar dwelt.
Later the pillars were cast down and their lamps broken by Melkor. Lands were broken and seas arose in tumult, destroying flame from the broken lamps poured out over the Earth, marring it, and the Valar fled Middle-earth for Valinor. At the site where Illuin fell the inland Sea of Helcar was formed, of which Cuiviénen was a bay.