The earliest recorded expansion of the Celts from the region north of the Alps was over northern Italy, and no historian supposes or suggests that the first Celtic occupation of northern Italy was earlier than about 600 B.C. This item ought to be borne in mind, for it has an important bearing on the date of the early Celtic migrations to Britain and Ireland. It was probably about the same time that they began to move westward across the Rhone, occupying the parts of France between the Garonne on the south and the English Channel on the north, which parts are specifically described by Julius Cæsar as Gallia Celtica, Celtic Gaul. Between 500 and 400 B.C. they spread south-westward into Spain, apparently more as conquerors than as colonists, for the resultant of the Celtic occupation of the Spanish Peninsula was the formation of a mixed people, partly Celts and partly Iberians, whom ancient writers distinguish from the Celts by giving them what we may call a hyphenated name, Celtiberians. We are not to imagine from this that Celtic conquests elsewhere were of an exterminating character, or that they did not result in a fusion of peoples. The notion that the migratory conquests of antiquity resulted in the displacement of one population by another is one of the favourite illusions of popular history. In Spain no doubt the Celtic element was relatively less numerous than in Gallia Celtica, and also perhaps the Celtic civilisation became less dominant, for the Iberians were in touch more or less with another and still more highly developed civilisation, that of the Phœnicians. That there was a somewhat distinctive civilisation south of the Garonne is clearly to be inferred from Cæsar's account, which tells us that the people of Celtic Gaul differed from those of Aquitaine, as well as from those of Belgic Gaul, in language, culture, and institutions. In the fourth century B.C. a second wave of Celtic migration poured over Italy. The Celts in this movement captured and destroyed the city of Rome. But they also appear to have destroyed the predominance of the Etrurians, and thereby to have facilitated the later imperial expansion of the Roman power. There was also an eastward Celtic movement along the Danube. In the third century B.C. the Celts overran most of what is called the Balkan Peninsula, including Greece, and in 278 B.C. large bodies of them passed over into Asia Minor and settled in the country which after them was named Galatia. Let it be noted at this point that so far as history casts light on the subject, the known period of Celtic expansion on the Continent lies within the years 650 B.C. and 250 B.C. We shall have to recur to this fact when we come to consider, in the following lecture, the probable date of the Celtic colonisation of Ireland. We shall see also that the evidence from archæology leads to the same conclusion as the evidence from history.