First Bulgarian Empire or The Golden Age of Bulgaria
Modern historiography admits that the language of the Ancient Bulgarians was from the Indo-Fergan linguistic group. At the formation of the Danube Bulgaria, the Bulgarians, who gave their name to the new state, were relatively lower in number compared to the Slavs. In the next 100-150 years this led to the gradual establishment of Slavonic (also of Indo-European origin) as a predominant language. Therefore, the modern Bulgarian language belongs to the group of Slavonic languages.
In the second half of the 9-th century the most impressive fact in the cultural history of Bulgaria and the other Slavonic countries was the creation and dissemination of a script and literature of the spoken Slav language. Two monk brothers of Bulgarian origin - Cyril (Constantine the Philosopher) and Methodius - created in Ohrid and disseminated among the Slavs, together with their disciples, the first Slavonic alphabet - Glagolic. For their contribution in spreading the Christianity, Cyril and Methodius were declared Saint Patrons of civilized Europe by the pope John Paul – II. Some of the disciples came to Bulgaria, where they were warmly welcomed and offered good conditions for work. Between 886 and 893 AD one of them – St. Clement of Ochrid created an ameliorated version – the Cyrillic alphabet. Prince Boris I Michail assigned the disciples with the mission to continue with the translation of the Holy Scripture from Greec and to educate thousands of priests to preach in Bulgarian language in local churches. These activities were concentrated mainly in the region of Pliska and in the region of Kutmichevitsa (Devol and Ochrid). From Bulgaria the Cyrillic script spread to other Slavic lands as well - present-day Serbia and Montenegro, Russia, Ukraine, Belarus, Republic of Macedonia and others.
The creation of the new alphabet provoked a severe reaction both from the German clergy and from Rome, which deemed that the Holy Scripture could be preached only in “the three holy languages” – Jewish, Greek and Latin. Cyril and Methidius successfully advocated before Rome the right of the Slavs to have a script and to perform religious services in their own mother tongue. Finally, Rome recognized the new language. Soon afterwards Bulgarian became the language of church, literature and official administration, and laid the foundation for the rich Medieval Bulgarian culture.
The conversion to Christianity and the creation of the Slavonic alphabet and literature accelerated the process of consolidation of the Bulgarian nation on vast geographical regions of the Balkan Peninsula – Moesia, Dobroudja, Thrace, the Rhodope Mountain and Macedonia.
The cities of Ochrid and Pliska, and subsequently the new capital city Veliki Preslav, became centres of Bulgarian culture, integral part of the Slav culture as a whole.
During the reign of King Simeon I the Great (893-927 AD) the Bulgarian State reached the peak of its political grandeur and power. It marked the "Golden Age of Bulgarian Culture". The country achieved significant territorial enlargement, its borders reached the Black Sea and the Aegean Sea. In the summer of 917 near the river Aheloy (North-Eastern Bulgaria) the Bizantine army was crushed during a spectacular military operation led by King Simeon I the Great. He proclaimed himself as a Roman Emperor. Hence, in the first half of 10th century Europe was deivided among the Christian Empires of the Bulgarians, Franks and Byzantines.
During the reign of Simeon's successors, Bulgaria was weakened by internal struggles. The Bizantine Empire took advantage of this weakness and in 871 AD invaded the Eastern part of Bulgaria, including the capital of Veliki Preslav. For this reason, the Bulgarian king Samuil (987 - 1014), son of the governor of of the Macedonian provinces of Bulgaria, mouved the capital to Ohrid (on the banks of the lake Ochrid).
In 1018, after prolonged wars, Bulgaria was conquered by the Byzantine Empire. From the very first years under Byzantine rule, the Bulgarians started fighting for their freedom. In 1186, the uprising led by two noble brothers - Assen and Peter, overthrew the domination of the Byzantine Empire. The Second Bulgarian Kingdom was founded, and Turnovo became the new capital. After 1186, Bulgaria was initially ruled by Assen, and after that by Peter.