The Teutonic nations form the second great group. They occupy nearly the whole of Central Europe to the north of the Alps, and extend through Holland and Flanders to within a short distance of the Straits of Dover. Denmark and the great Scandinavian peninsula, as well as Iceland, belong to the same group, and {20} the bulk of the inhabitants of the British Islands are likewise generally included in it. The latter, however, should rather be described as a mixed race, for the aboriginal Celtic population of these islands, which now exists pure only in a few remote districts, has amalgamated with Anglo-Saxon and Danish invaders, and the language of the latter has become mixed with mediæval French, the resulting idiom being almost as much Latin as Saxon. The development of national characteristics has been favoured by the isolation in which the inhabitants of the British Islands found themselves, and they differ essentially from continental neighbours—the Scandinavians, Germans, and Celto-Latins—in language and customs. The Slavs, or Slavonians, form the third group of European nations. They are less numerous than the Greco-Latins, but the territories they occupy are far more extensive, for they spread over nearly the whole of Russia, over Poland, a large portion of the Balkan peninsula, and about one-half of the Austro-Hungarian monarchy. All the great plains to the east of the Carpathians are inhabited by Slavs, either pure or mixed with Tartars and Mongols. To the west and south of the mountains the race is split up into numerous small nations, and in the valley of the Danube these come into contact with Rumanians, as well as with Turks and Magyars, the two latter being of Asiatic origin, and these separate the Slavonians of the north from the Slavonians of the south. In the north, Finns, Livonians, and Lithuanians interpose between the Slavonians and the Germanic nations.[4] Race and language, however, are not always identical. Members of one race frequently speak the language of another, and race and linguistic boundaries, therefore, differ frequently. As for the political boundaries, they scarcely ever follow those natural features which would have been selected had their settlement been intrusted to the spontaneous action of the different nations. They hardly ever coincide with the boundaries of races or of languages, except in the case of a few high mountain ranges or of arms of the sea. On many occasions the countries of Europe were arbitrarily split up in consequence of wars or diplomatic arrangements. A few peoples only, protected by the nature of their country as well as {21} by their valour, have maintained their independence since the age of great migrations, but many more have been swept away by successive invasions. Many others, again, have alternately seen their frontiers expand and contract more than once even during a generation.