Ghost of a flea

Mordor is not mentioned in the histories of Middle-earth before the end of the first millennium of the Second Age, when Sauron chose it as his dwelling place. While its natural defences must have influenced his decision, we are told that the main reason for his choice was Orodruin, the great volcano that lay in the central regions of the Plateau of Gorgoroth, and which Sauron used in his sorcery, including the forging of the One Ring.