Hecataeus of Miletus
The first recorded use of the name of Celts – as ("Keltoí") – to refer to an ethnic group was by Hecataeus of Miletus, the Greek geographer, in 517 BC when writing about a people living near Massilia (modern Marseille). In the 5th century BC, Herodotus referred to "Keltoi" living around the head of the Danube and also in the far west of Europe.