Our subject is historical geography, and neither ethnology nor political history, except so far as either national migrations or political changes produce a directly geographical effect. ♦The Wandering of the Nations.♦ The great movement called the Wandering of the Nations, and its results in the settlement of various Teutonic nations within the bounds of the Roman Empire, concern us now only so far as they wrought a visible change on the map. The exact relations of the different tribes to one another, the exact course of the migrations which led to the final settlement of each, belong rather to another branch of inquiry. But there are certain marked stages in the relations of the Empire to the nations beyond its borders, certain marked stages in the growth and mutual relations of those nations, which must be borne in mind in order to explain their settlements within the Empire. ♦Changes in the nomenclature of the Teutonic nations.♦ It will be at once seen that the geography and nomenclature of the German nations in the third century is for the most part quite different from their geography and nomenclature as we find it in Cæsar and Tacitus. New names have come to the front, names all of which play a part in history, many of which remain to this day; and, with one or two exceptions, the older names sink into the background. It is therefore hardly needful to go through the ethnology and geography of Tacitus, or to deal with any of the controverted points which are suggested thereby. We have to look at the German nations purely in their relations to Rome. ♦Warfare on the Rhine and the Danube.♦