Thomas Arnold & Louis Brehier 
The Cambridge Medieval History – Book XV [EPUB ebook] 
The Eastern Roman Empire from Isaac I to Andronicus

 WHILE the Germans impressed their characteristic stamp on both the medieval and modern history of Western Europe, it was reserved for the Eastern Slays, the Russians, to build a great empire on the borderlands of Europe and Asia. But the work of civilization was far more difficult for the Russians than for the German race. The barbaric Germans settled in regions of an old civilization among the conquered Romans and Romanized peoples, whereas the geographical and ethnical surroundings entered by the Eastern Slays were unfavourable, in so far as no old inheritance existed there to further any endeavours in civilization; this had to be built up from the very foundations. Boundless forests, vast lakes and swamps, were great obstacles to the colonization of the immense plain of eastern Europe, and the long stretch of steppes in southern Russia was for many centuries the home of Asiatic nomads, who not only made any intercourse with Greek civilization impossible but even endangered incessantly the results of the native progress of the Russian Slavs.
 
 The growth of the Russian empire implies not only the extension of the area of its civilization but also the absorption of many elements belonging to foreign races and speaking foreign tongues, and their coalescence with the dominant Russian nation…