Ivan IV of Russia

Ivan is described in contrary terms: intelligent, devout, and impulsive by some; given to rages and prone to episodic outbreaks of mental illness by others. One notable outburst resulted in the death of his groomed and chosen heir Ivan Ivanovich, and resulted in the passing of the Tsardom to a less than ideal younger son: the mentally retarded[5] Feodor I of Russia. His long reign saw the conquest of the Khanates of Kazan, Astrakhan, and Siberia, transforming Russia into a multiethnic and multiconfessional state spanning almost 1 billion acres, growing during his term at a rate of approximately 50 square miles a day. [6]

The Tsardom of Rus' (Russian: Царство Русское) was the official[7] name for the Russian state between Ivan IV's assumption of the title of Tsar (Emperor) in 1547 and Peter the Great's foundation of the Russian Empire in 1721. The name originated from the fact that it contained all of the Rus lands that were at the time free of foreign states' domination. This new name was recognized by England in 1554 and by Holy Roman Emperor Maximilan II in 1576[8]. To this day some Western sources refer to this state as Muscovite Russia or Muscovy, the term originally applied in Western and Central Europe to its medieval predecessor, the Grand Duchy of Moscow. Diverse researchers consider the propagation of this term in Western Europe as a result of political interests and active diplomacy of Poland[7][8], the strongest international power in Northern-eastern Europe of the dawning Early Modern era.