Olga was a regent of Kievan Rus' for her son Sviatoslav from 945 until 960. Following her baptism, Olga took the name Elenа. She is known for her subjugation of the Drevlians, a tribe that had killed her husband Igor. Even though it was her grandson Vladimir who adopted Christianity and made it the state religion, she was the first ruler to be baptized.

Kievan Rus', also known as Kyivan Rus', was a state and later an amalgam of principalities in Eastern and Northern Europe from the late 9th to the mid-13th century. The name was coined by Russian historians in the 19th century. Encompassing a variety of polities and peoples, including East Slavic, Norse, and Finnic, it was ruled by the Rurik dynasty, founded by the Varangian prince Rurik. The modern nations of Belarus, Russia, and Ukraine all claim Kievan Rus' as their cultural ancestor, with Belarus and Russia deriving their names from it, and the name Kievan Rus' derived from what is now the capital of Ukraine. At its greatest extent in the mid-11th century, Kievan Rus' stretched from the White Sea in the north to the Black Sea in the south and from the headwaters of the Vistula in the west to the Taman Peninsula in the east, uniting the East Slavic tribes.