longer part of the upper world. Rather they were the gods who dwelt underground in Tartarus, and as such, they may have been thought of as "gods of the underworld", who were the antithesis of, and in opposition to, the Olympians, the gods of the heavens. Hesiod called the Titans "earth-born" (chthonic), and in the Homeric Hymn to Apollo, Hera prays to the Titans "who dwell beneath the earth", calling on them to aid her against Zeus, just as if they were chthonic spirits. In a similar fashion, in the Iliad, Hera, upon swearing an oath by the underworld river Styx, "invoked by name all the gods below Tartarus, that are called Titans" as witnesses. They were the older gods, but not, apparently, as was once thought, the old gods of an indigenous group in Greece, historically displaced by the new gods of Greek invaders. Rather, they were a group of gods, whose mythology at least, seems to have been borrowed from the Near East (see "Near East origins," below). These imported gods gave context and provided a backstory for the Olympian gods, explaining where these Greek Olympian gods had come from, and how they had come to occupy their position of supremacy in the cosmos. The Titans were the previous generation, and family of gods, whom the Olympians had to overthrow, and banish from the upper world, in order to become the ruling pantheon of Greek gods. For Hesiod, possibly in order to match the twelve Olympian gods, there were twelve Titans: six males and six females, with some of Hesiod's names perhaps being mere poetic inventions, so as to arrive at the right number. In Hesiod's Theogony, apart from Cronus, the Titans play no part at all in the overthrow of Uranus, and we only hear of their collective action in the Titanomachy, their war with the Olympians. As a group, they have no further role in conventional Greek myth, nor do they play any part in Greek cult. As individuals, few of the Titans have any separate identity. Aside from Cronus, the only other figure Homer mentions by name as being a Titan is Iapetus. Some Titans seem only to serve a genealogical function, providing parents for more important offspring: Coeus and Phoebe as the parents of Leto, the mother, by Zeus, of the Olympians Apollo and Artemis; Hyperion and Theia as the parents of Helios, Selene