Руси, or the Rus', were a group of East Slavic tribes that played a significant role in the early history of Eastern Europe. They are often associated with the formation of the first East Slavic state, known as Kievan Rus, which emerged in the 9th century. The Rus' were known for their trade routes, connecting the Baltic Sea to the Black Sea, and their interactions with various cultures, including the Vikings and Byzantines. The term "Руси" is also linked to the origins of the modern nations of Russia, Ukraine, and Belarus. The Rus' people were instrumental in the spread of Christianity in the region, particularly after the baptism of Prince Vladimir in 988. Their legacy continues to influence the cultural and historical identity of these nations today.