It need hardly be re-stated here that the Celts are a linguistic offshoot of a prehistoric people whose descendants--also in the line of language--comprise many ancient and modern populations in Europe and Asia. It would be out of place now to discuss the central location from which the various branches of this prehistoric people spread themselves over so wide an area. Indeed, it is a facile and fanciful assumption to suppose that the spreading took place from one central habitat. It is enough to say that, whereas the earlier philologists took for granted that the original population, before its division into various linguistic groups, was located in Western Asia, the later philologists are strongly inclined to place its home in Europe, in the region south-east of the Baltic Sea. The oldest known geographical descriptions of Europe are those of Hecatæus, who flourished about 500 years before the Christian Era, and Herodotus, about half a century after him. Their knowledge of the European mainland, north of the countries bordering on the Mediterranean and its inlets, was of the most vague and general kind. They divided the whole of northern and middle Europe between two peoples, the Scythians in the eastern, and the Celts in the western parts. They also knew of the Iberians in the south-west, in the Spanish peninsula and the adjoining parts of France. Herodotus, however, recognised to the west of the Celts a people whom he calls Kunēsioi and Kunētai, and in the furthest north of Europe a population distinct from the Celts and Scythians, but unknown to him by any name of their own, for he calls them Hyperboreans, _i.e._, out and out northerns. In the time of Eratosthenes, about 200 B.C., this knowledge does not appear to have been very much increased among the Greeks. They knew, however, of the existence of the islands of Ireland, which they called Ierne, and Britain, which they called Albion, and also of a country beyond the Baltic; but they still divided the northern mainland of Europe between the Celts and the Scythians. I have already remarked how ancient Irish tradition ignores the Celtic origin and affinities of the Irish. We may go farther and say that our ancient writers, when they set about exploring the geographical knowledge of the world that came to them in Latin writings, had it very definitely in their minds that the Irish were not of Celtic origin; for, of the three great populations of northern and western Europe known to the oldest classical writers--the Iberians, the Celts, and the Scythians--they excluded the Celts, and included the other two, some selecting the Iberians and others the Scythians as the ancestral people from which the Gaels were descended.