Russian Tsardom refers to the period in Russian history when the country was ruled by a series of monarchs known as tsars. This era began in the early 16th century with Ivan IV, also known as Ivan the Terrible, who was the first to officially use the title of tsar. The tsardom lasted until the early 20th century, culminating in the abdication of Nicholas II during the Russian Revolution in 1917. During the tsardom, Russia expanded its territory significantly, becoming one of the largest empires in history. The tsars wielded absolute power, often supported by the Orthodox Church and a noble class. This period saw significant cultural, political, and social developments, including the establishment of the Romanov dynasty, which ruled for over 300 years.