Oprichnina was a policy implemented by Ivan IV, also known as Ivan the Terrible, during his reign from 1547 to 1584. This policy involved the creation of a separate territory and administration within Russia, governed by the Oprichniki, who acted as both enforcers and spies for the tsar. The Oprichnina was characterized by extreme repression, including political purges and acts of terror against perceived enemies, which reflected Ivan IV's belief in absolute power and control.