Tsar Simeon the Great (ruled 893-May 27, 927) was 27 when he took the throne of Bulgaria from his brother Vladimir, the son of Prince Boris, who was deposed and blinded by his own father after his attempt to return to paganism.
After he received his education at the famous Magnaur Academy in Constantinople, Simeon was prepared to become the head of the Bulgarian Church, only suddenly to become Tsar instead. To break away from Byzantine religious influence he replaced the Greek liturgy with Bulgarian. He moved quickly and forcefully. The newly devised Cyrillic alphabet enabled the use of the Bulgarian language in administration, in literature and liturgy, and in 893 a national council adopted Bulgarian as official language in the Bulgarian state and church. The written Bulgarian language was soon firmly established with translations from Greek and new hagiographies. Learning centres in Preslav and Ohrid created works of literature in Slavic, which was the first time in Europe that a language other than the traditionally sacred tongues Hebrew, Latin and Greek was used.
The capital was moved from Pliska (still somewhat paganist) to Preslav.
In 893 the Byzantines decided to move the market for Bulgarian goods out of Constantinople to Thessaloniki. There, the Bulgarian tradesmen would have to pay higher taxes. The war that followed (the first war in Europe fought solely over economic differences) ended after the Bulgarians crushed the Byzantines in 896 near Bulgarophygon in Eastern Thrace. The market was returned to Constantinpole and the Byzantine Emperor had to pay annual tribute to Bulgaria. After a series of battles the border of the Bulgarian state was within twenty kilometers of Thessaloniki.
Simeon was trying to replace Byzantium and build a Bulgaro-Byzantine empire. By 913 he was at the gates of Constantinople. Having become the most powerful monarch in eastern Europe, Simeon assumed the style of "Emperor and Autocrat of all the Bulgars and Greeks", a title which Pope Formosus was quick to recognize. In the imperial palace he received the patriarch's blessing and the title of Tsar of Bulgaria. Simeon lured the Serbian king and the Pecheneg chief to his side, away from an attempted alliance with the Byzantines. On August 20, 917 by the river Achebi, between Anchialo and Messembria, the imperial army suffered a heavy defeat. He negotiated with his Arab neighbors, the Byzantine Emperor, the Patriarch and the Pope, but his dream to become ruler of both Bulgaria and Byzantium was cut short. After demolishing many Byzantine towns while preparing to attack Constantinople, he died of a heart attack on May 27, 927.
Simeon the Great had turned Bulgaria into the most powerful Slavic state in Europe. He became a patron of arts and letters as this Bulgarian culture saw its Golden Age. He is thought of as the Bulgarian Charlemagne.
After the death of Simeon, Bulgarian power declined owing to internal dissensions; the land was distracted by the Bogomil heresy, and a separate or western empire, including Albania and Macedonia, was founded at Ochrida by Shishman, a boyar from Trnovo.