For a time it appeared that the Mongols were settling (early 1,300's), becoming civilized, and embracing Christianity. But then they converted to Islam en masse, and renewed the practice of seeking out any settlement to burn, kill and capture victims for the slave market, which continued into the 18th century. Eventually Russia gets enough strength to slaughter much of the horde by the Caucasus. Shortly afterwards, this horde together with the Turks manages to take Moscow, which they pillage, burn and then kill 150,000 or so civilians. This last episode they termed "revenge", as if this had been some sort of tit for tat fight all along. The Cossacks make their appearance during this phase as militarized bands who wander the unsettled areas of Russia that were periodically swept by the Tatars. Their allegiance to the Eastern Orthodox Church would make them a natural enemy of the Tatars.
During this period, Russia is anxious to bring in learning from the West and various craftsmen and artisans were enticed to come to Russia to further this aim. Trade and friendly relations begin with England and Holland, although clashes with Poland and Sweden are the norm. Considering the propaganda I was taught growing up, the distinctive here is that all the learning that arrives in Russia is from the West, and it is to the West that Russia turns when it seeks learning. Another contrasting item is the relatively constructive role of the Russian church. I suspect that one of the reasons is the rules regarding married clergy in the Russian church. Whatever the cause, it seems that the Russian clergy were constructively leading their flocks during periods where the Roman clergy were sexually abusing and robbing those who were put into their care. This is likely the reason that the Reformation was a Western European phenomenon.