The existence of Celts in the Iberian Peninsula is at-tested by the linguistic evidence and by the information provided by the Graeco-Latin historians and geographers. The earliest descriptions of the Celts, apart from the disputed Periplum of Avienus, come from Herodotus, who already in the 5th century BC said they were to be found in the Iberian Peninsula. However, it was not until the latter centuries of the pre-Christian era that the names of the peninsular Celtic tribes and the territories they occupied were known: the Celtiberian and Beron tribes in the Eastern Meseta, the Iberian System and the Middle Valley of the Ebro; the Celtic tribes in the Southwest; and various groups of Celtic filiation, clearly differentiated from other non-Celtic tribes, in the Northwest, Galicia and the North of Portugal. According to the literary sources (Chapter II, 1.1), Celtiberia was a large area in the interior of the Iberian Peninsula. There was not always unanimous agreement about its ter-