Левобережная Украина
The term was adopted in the 17th century by the Tsardom of Russia to refer to the Cossack Hetmanate of Left-bank Ukraine, when the latter fell under Russian protection after the Treaty of Pereyaslav (1654). From 1654 to 1721, the official title of Russian tsars contained the language (literal translation) "The Sovereign of all Rus': the Great, the Little, and the White."