The Tuatha Dé Danann were descended from Nemed, leader of a previous wave of inhabitants of Ireland. They came from four cities to the north of Ireland—Falias, Gorias, Murias and Finias—where they taught their skills in the sciences, including architecture, the arts, and magic, including necromancy. According to Lebor Gabála Érenn, they came to Ireland in dark clouds and landed on the mountains of [the] Conmaicne Rein in Connachta, otherwise Sliabh an Iarainn, and they brought a darkness over the sun for three days and three nights. They immediately burnt the ships so that they should not think of retreating to them, and the smoke and the mist that came from the vessels filled the neighbouring land and air. Therefore it was conceived that they had arrived in clouds of mist.