Lough Erne (Loch Éirne) appears to be named after an ancient population group called the Érainn, or after a goddess from which the Érainn took their name. Since tribes were often named after a divine ancestor, T. F. O'Rahilly suggested that the Érainn took their name from a goddess named Érann and that Loch Éirne probably means "lake of (the goddess) Érann". O'Rahilly and other scholars have connected these names to Ériu (modern Éire), the goddess after which Ireland is named. He writes that the earlier forms of these goddess names were Everna/Iverna and Everiu/Iveriu and that both come from "the Indo-European root "ei-", implying motion". In his view Érann and Ériu would thus appear to mean "she who travels regularly", explained as "the sun-goddess, for the sun was the great celestial Traveller". Alternatively, John T. Koch suggests that Ériu was a mother goddess whose name comes from an Indo-European word stem meaning "fat, rich, fertile".