It doesn't matter whether they oppressed or protected. A person, especially a Russian, is such a being that they are not capable of living under someone else's "yoke" (figuratively speaking). Sooner or later, what happened to the Tatars and Mongols would have inevitably happened. Some country would have put an end to this whole thing with tribute and the like. Unfortunately for the Mongols, that country turned out to be Russia. When defending themselves, our people will always give the invaders a final blow to their territory, so that they won't dare to do it again in the future. Well, and... they miscalculated a bit... :D