By the late 900s A.D., many of the Slavs began to practice Christianity. Their interaction with the Byzantine Empire brought them into close contact with the faith.
The first member of the royal family to be converted to Christianity was a Kievan Princess by the name of Olga. Her grandson Vladimir eventually became the Grand Prince. Vladimir sent out an embassy to search out a true form of religion. This embassy visited many different religions, and determined that only Eastern Orthodox held the keys to the continued success of their kingdom.
Upon their return, Grand Prince Vladimir became converted to Eastern Orthodox, and ordered that all his people also convert to the new faith. Their conversion to Eastern Orthodox strengthened their ties with the Byzantines, and helped bring their culture to new heights.
The Byzantines taught the Slavs new skills in art and building, they built schools, taught the Slavs how to write, and helped them make great advancements in technology and science.