Volodymyr the Great, also known as Volodymyr I of Kyiv, was a ruler of the Kievan Rus' from 980 to 1015. He is best known for his role in the Christianization of the region, adopting Christianity as the state religion and promoting its spread among his people. This significant change helped to unify the diverse tribes under his rule and established stronger ties with Byzantine Empire. Volodymyr was also a skilled military leader, expanding the territory of the Kievan Rus' through various campaigns. His reign is often seen as a golden age for the region, as he fostered trade, culture, and the arts, laying the foundation for the future development of Ukraine and Russia.