Nogai Horde
Annually, Moscow mobilized in the spring up to 65,000 soldiers for boundary service. The defensive lines were applied, consisting of a circuit of fortresses and cities. Cossacks and young noblemen were organized into sentry and patrol services that observed Crimean Tatars and nomads of Nogai Horde on the steppe. About 30 major Tatar raids were recorded into Muscovite territories between 1558-1596.