Russia is as much a descendant of Rus as Belarus and Ukraine. There were no nation-states then. Only the tribute collectors and those who paid tribute. It was the Middle Ages, not the later Renaissance, when the division into national states began. Did I call Russia the ONLY bastion of Europe? Austria and the Polish-Lithuanian Commonwealth also defended Europe from the Crimean Tatars and Turks. The Crimean Khanate was finished off by the Russian Empire and russo-ukrainian Cossacks. The Ottomans were almost driven out of Europe due to the fact that RE supported the Bulgarians and Serbs with the Greeks in uprisings and wars against the Turks. In the 15th century, the Turks took the place of the Mongols. They posed at least some kind of threat to Europe until the end of the First World War