Ivan IV, or Ivan the Terrible, was an influential ruler in the late sixteenth century. His father, Ivan the Great, had driven the Mongols from Moscow. In 1547 he took control of the entire kingdom of Russia. This was the first time that centralized government was introduced in Russia. Ivan had a traumatic childhood. When he took the throne, he imprisoned and executed many people. Accomplishments of Ivan IV include: establishing a standing army, revising the legal code, including instituting tax reforms, creating a parliament and council of nobles, formalizing the position of the Russian Church, ushering in the beginning of the Russian feudal serfdom system, expanding Russian territory, commissioning the building of St. Basil's Cathedral.