The first recorded use of the name 'Celts' – as Κελτοί (Keltoi) in Ancient Greek – was by Greek geographer Hecataeus of Miletus in 517 BC, when writing about a people living near Massilia (modern Marseille), southern Gaul. In the fifth century BC, Herodotus referred to Keltoi living around the source of the Danube and in the far west of Europe. The etymology of Keltoi is unclear. Possible roots include Indo-European *kʲel 'to hide' (seen also in Old Irish ceilid, and Modern Wels…