Olga of Kiev

As regent, Olga avenged Igor's murder by deceiving and killing Drevlian ambassadors, then besieging and burning their capital, Iskorosten. She used birds carrying flaming materials to set the city ablaze, subjugating the tribe.

Olga implemented a system of fixed tribute amounts and designated collection points (pogosts) across Kievan Rus. This reform standardized taxation, reduced corruption, and prevented the arbitrary exactions that had led to Igor's death.

Olga traveled to Constantinople and was baptized into Christianity by Emperor Constantine VII and Patriarch Polyeuctus, taking the name Helena. She became the first ruler of Kievan Rus to convert to Christianity.