A people in south Russia. They were descended from refugees from religious persecution in Poland and Muscovy, and from peasants fleeing the taxes and obligations of the feudal system. Settling in mainly autonomous tribal groups around the rivers Don and Dnieper, they played an important role in the history of the Ukraine. A frontier lifestyle encouraged military prowess and horsemanship, males aged 16–60 years being obliged to bear arms. They were democratic, directly electing their leaders or hetmen. Their relations with Russia included military service and military alliance, especially against the Turks, but there were rebellions against Russia under the leaderships of Stenka Razin (1667–69), Iran Mazeppa (1709), and Yemelyan Pugachev (1773–74). Ukrainian Cossackdom experienced a revival following the breakup of the Soviet Union in 1991. There are 15,000 registered Cossacks in the Ukraine.