Russia has been a defender of civilization since the time they drove back the Muslim hordes from central Asia.Which period? Which battles? (Just curious.)
Both before and after the fall of Constantinople. The Russians beat back the Tartars several times.
There's a brief summary here:
http://www.mainlesson.com/display.php?author=bergen&book=russia&story=decline
The Russians also managed to hold off the Grand Turk after he had captured Constantinople and Trebizond.