Another theory is that "Tehran" derives from Tiran/Tirgan, "the abode of Tir", the Zoroastrian equivalent of Hermes). The ancient  Parthian town of Tiran had a neighbour, Mehran ("abode of Mehr/Mithra", the Zoroastrian sun god). Both of these were mere villages in the suburbs of the great city of Ray/Rhages. Mehran still exists as a residential district in Greater Tehran, as well as Ray, which forms the southern suburbs of Tehran.