Oprichnina

The oprichnina (Russian: опри́чнина, ) is the period of Russian history between 1565 and 1572 during which Tsar Ivan the Terrible instituted a domestic policy of secret police, mass repressions, public executions, and confiscation of land from Russian aristocrats. The six thousand political police enforcing the policy were called oprichniki, and the term oprichnina also applies to the secret police organization and to the territory in which, during that period, the Tsar ruled directly and in which his oprichniki operated.