Cöln-Berlin, the marches of Brandenburg, East and West Prussia--in
fact, all the now Germanized lands to the east of the Elbe--owe their
Teutonic character to a great reflux, a reconquest so to speak, which
is barely mentioned in the usual textbooks of German history, yet
which is one of the most noteworthy phenomena in the development of
modern Europe. At the beginning of the fourth century German tribes
(German in the widest sense of the term) occupied the broad expanse
from the Rhine to the Dwina and the head-waters of the Dnieper. A
century later they had receded as far as the Vistula. Still another
century later, about 500, the German linguistic domain was bounded on
the east by the Ens, the Bohemian Hills, the upper Main, the Saal and
the Elbe. The downfall of the Thuringian kingdom was the occasion of
Slavic encroachments even on the left bank of the Elbe between Stendal
and Lüneburg. This German recession, which boded the Slavization not
only of Eastern but also of Central Europe, was due to various causes,
many of which are veiled in the impenetrable darkness which still
hangs over the early Middle Ages. The chief causes were undoubtedly
the Germanic migration over the Roman world and the settlement of the
Franks in Northern Gaul and the Saxons in England.

But with the Carolingian dynasty came a new era. Charles Martel,
Pepin and Charlemagne aspired to universal monarchy. Not content with
France, Northern Spain, Italy and Germany proper, Charlemagne, as we
have already seen, recaptured the middle Danube. His successors in
Germany, the Saxon, Franconian and Swabian emperors, continued the
impulse, but gave it in the main a different direction. Instead
of moving toward the south-east, where they would have encountered
stubborn opposition from the already compact Hungarian nationality,
they chose for their field of colonization (or recolonization) the
east and north-east. Throughout the eleventh, twelfth, thirteenth