THE IRON AGE The Celtic (Iron Age) Immigration.—This ancient people remained in undisturbed possession of the country down to about 400-35o B.C. It is possible that there were occasional immigrations such as a gold-producing country would naturally attract ; but if so these became absorbed in the aboriginal population, and cannot now be isolated. But at the date indicated a much more formid able immigration took place, doubtless only one phase of the movements of peoples in central Europe, of which the Gaulish sack of Rome in 390 B.C. and the attack on Delphi about ioo years later were outstanding incidents. The Celtic people seems to have had its origin in the regions between the head-waters of the Rhine and the Danube. There they developed their peculiar linguistic characteristics, which is the chief if not the only common mark of "Celticity" in the modern world. They seem early to have become acquainted with the iron-smith's craft, and with the aid of their iron weapons they subdued one by one the petty peoples of the area of Europe north of the Alps. Over these peoples they spread a veneer of Celticity ; they Celticized them in speech, in religion, and in organization : but could not make any very great modification in their racial affinities. This explains the racial diversity which underlies the superficial unity of the Celtic peoples, and which makes it difficult to determine to what people the term "Celtic" most fittingly belongs.
A community—or more probably, several communities—of this people effected an entrance into Ireland in or about the middle of the 4th century B.C. They were probably few in numbers ; but they had the advantage of a superior military organization, and, especially, of iron weapons. In time they effected a complete revolution in the life of the country. Their Celtic speech com pletely ousted the aboriginal Pictish. Their Indo-European patri archal organization took the place of the aboriginal matriarchate. New gods and new methods of government, new arts and new crafts, were introduced. The aborigines were reduced to vassalage, which, though mitigated with the establishment of Christianity, was never completely terminated until conqueror and conquered alike were subdued by the Norman. The newcomers were a tall fair people, of Nordic extraction, and contrasted physically with the aborigines. The contrast was maintained, as we cannot doubt, by restrictions on intermarriage. In the literature which a little later began to come into being, an aristocratic product, the distinc tion between fair and dark people is of paramount importance.
Every person who is spoken of with respect, save for a number of individuals of exceptional character who "prove the rule" much more clearly than in most cases of the kind, is described as being tall and fair, with long flowing locks. Every person who for any reason is spoken of with disdain is described as being short, dark, and with close-cropped hair.
The culture which the newcomers brought into the country belongs to the later stage of the iron culture of Europe, which goes by the name of La Tene. The earlier phase of the iron culture, called by the name of Hallstatt, is not represented in Ireland save by a few stray objects which came in by way of trade or by mere accident, and do not indicate a permanent settle ment. This enables us to assign a date to the Celtic invasion with tolerable exactness. The legends of the landing of the invaders, attracted by the country's store of gold, may at least be historical in that they represent the landing as taking place in the south-east corner of the island : the place where the gold-bearing gravels are to be found.