ARMY OF IVAN IV

This map from Beskrovni's Atlas of Russian military history shows in blue the typical attack routes from Crimea. The Nogai Tatars had other routes nearer the Volga. It shows in solid red the first defensive lines as of 1571 and in dotted red some of the later lines up to the reign of Boris Gudunov. More extensive and elaborate defensive lines were built further south during the first half of the 17th century.