Many of the stories about bogatyrs revolve around the court of Vladimir I of Kiev (958–1015) and are called the Kievan Cycle. The most notable bogatyrs or vityazes served at his court: the trio of Alyosha Popovich, Dobrynya Nikitich and Ilya Muromets. Each of them tends to be known for a certain character trait: Alyosha Popovich for his wits, Dobrynya Nikitich for his courage, and Ilya Muromets for his physical and spiritual power and integrity, and for his dedication to the protection of his homeland and people. Most of those bogatyrs adventures are fictional, and often included fighting dragons, giants and other mythical creatures. However, the bogatyrs themselves were often based on real people. Historical prototypes of both Dobrynya Nikitich (the warlord Dobrynya) and Ilya Muromets are proven to have existed.