The title "Grand Prince of Kiev" refers to the ruler of the medieval state of Kievan Rus, which existed from the late 9th to the mid-13th century. This title was held by various princes, with Vladimir the Great and Yaroslav the Wise being among the most notable. The Grand Prince was responsible for unifying the region, overseeing trade, and promoting the spread of Christianity. The Grand Prince of Kiev was often seen as the most powerful leader in Eastern Europe during its peak. The position was hereditary, typically passed down through the ruling family, and it played a crucial role in the political and cultural development of the region. The title eventually declined in significance as Mongol invasions disrupted the power structure of Kievan Rus.