Let's discuss Cossacks. Post stories, music, and comment on modern Cossacks emerging in Russia and Ukraine.
And zealously so, at least Ukrainian cossacks. Protectors of holy orthodoxy and everything.
They didn't appear out of nowhere. Poles/Lithuanians (and partially Muscovites, in what's now Sloboda Ukraine) knew that their Eastern frontier had to be defended somehow, and so encouraged people settling on those dangerous lands by granting them various freedoms. Since peasant's life in the mainland wasn't particularly nice, especially since szlachta was becoming more and more powerful and exploitative, a lot of people decided to take the chance. Some plainly ran away and settled down.
Living on an open frontier where even an ordinary peasant has to learn to use a musket changes people rapidly. Tatar attacks annoyed some so much that they decided to start fighting back. Thus eventually cossacks were born. Some of the more hardcore people created various hosts deep into steppes which served as small bases to get rest and resupply.
Mind you, the frontier back then wasn't particularly far away. Bratslav was already almost on the border, for example. Kaniv was a small fort, so was Cherkasy.
When Europe was stuck in the system of Merchant capitalism and Feudalism the Cossacks threw out the merchants. Established a free state in which the peasant was as free as the king and the land and crop was his own.