Simeon I “The Great” of Bulgaria

Emperor of the Bulgarians and Romans. Tsar Simeon (also Symeon) I 'The Great' ruled over Bulgaria from 893 to 927, during the First Bulgarian Empire. Simeon's successful campaigns against the Byzantines, Magyars and Serbs led Bulgaria to its greatest territorial expansion ever, making it the most powerful state in contemporary Eastern and Southeast Europe. His reign was also a period of unmatched cultural prosperity and enlightenment later deemed the Golden Age of Bulgarian culture. Simeon was born in c865, as the third son of Knyaz Boris I of Krum's dynasty. As Boris was the ruler who Christianized Bulgaria in 865, Simeon was a Christian all his life. Because his eldest brother Vladimir was designated heir to the Bulgarian throne, Boris intended Simeon to become a high-ranking cleric, possibly Bulgarian archbishop, and sent him to the leading University of Constantinople to receive theological education when he was thirteen or fourteen. He took the name Simeon as a novice in a monastery in Constantinople. During the decade (ca. 878–888) he spent in the Byzantine capital, he received excellent education and studied the rhetoric of Demosthenes and Aristotle. He also learned fluent Greek, to the extent that he was referred to as "the half-Greek" in Byzantine chronicles. He is speculated to have been tutored by Patriarch Photios I of Constantinople. Source : Wikipedia