We have seen in the last chapter that different types of leaf-shaped swords have been disseminated throughout various quarters of Europe, and we have found reason for believing that in Celtic lands at least their appearance signified a hostile invasion. If, as may well be the case, the same is true of other parts of Europe, we are dealing with a series of invasions, all starting from somewhere within the Celtic cradle, and affecting almost every part of the continent. Our purpose in this work is not so much to record evidence as to interpret it, to restore the main features of early history rather than to describe archæological remains. Now the backbone of history is chronology, and we cannot interpret our evidence satisfactorily unless we can place it in its true chronological setting. In discussing the seven types of swords an endeavour was made to arrange them in an orderly sequence, and thus to set up a relative chronology. In this chapter a positive system of dating will be attempted. It is clear that it is to the south-east that we must first look for help, for in Greek lands documentary evidence reaches back some centuries further than it does elsewhere in Europe, and is preceded by an immense mass of tradition, much of which clearly belongs more to legend than to myth. These legends, moreover, have received intensive study, and their contents have been brought into line with archæological data.[353] Further than this we have the two swords found in Egypt, one of them engraved with a monarch’s name, so that a study of these south-eastern specimens should enable us to obtain one point, at least, in our system of dates. Now it has been pointed out by Sir William Ridgeway[354] that certain people, whom he calls “Achæans,” entered Greece from the north, bringing with them certain elements of culture, which can best be matched in the Danube basin. These, according to the traditions preserved in the Iliad, were the immediate ancestors of the heroes of the Trojan War. Recently Dr. Wace,[355] who has made a careful study of the pre-Hellenic remains of the mainland of Greece, especially of the pottery, has pointed out that there is but one break in the ceramic evolution of that region, the introduction of geometric ware. This is, he believes, best explained by equating it with the Dorian invasion, which took place some generations after the siege of Troy. Dr. Wace has certainly made out a strong case, and we must accept his view that no invasion, in the strict sense of the term, preceded that of the Dorians; but while he would have us scrap the “Achæan” hypothesis in its entirety, we must, I think, consider awhile before dismissing all the evidence that Sir William Ridgeway has accumulated.