the rise of nationalism in russia. and now that extends to the resurgence of a legendary group of militants. fierce horsemen with roots deep in the kremlin. called the cossacks. they re revered in russia. much like cowboy or minute men are here in the united states. and as our partners reveal, despite complicated legacies that are both violent and tragic, the cossacks are back. reporter: it was one of the most shocking images from the 2014 olympics. a group of punk rockers beaten by men with whips. the women and their supporters are members of the now famous band pussy riot. the band and their friends, male and female, went to sochi to make a music video criticizing