The First Bulgarian Empire was a medieval state that existed in Southeastern and southeastern Central Europe between the 7th and 11th centuries AD. It was founded in 680–681 after a group of Bulgars, led by Asparuh, moved south to the northeastern Balkans, and secured Byzantine recognition and their right to settle south of the Danube by defeatingpossibly with the help of local South Slavic tribesthe Byzantine army led by Constantine IV. During the 9th and 10th century, Bulgaria reached the height of its power and stretched from the Danube Bend to the Black Sea and from the Dnieper River to the Adriatic Sea, becoming a major power capable of competing with the Byzantine Empire.

As the state solidified its position in the Balkans, it entered into a centuries-long interaction, sometimes friendly and sometimes hostile, with the Byzantine Empire. Bulgaria became Byzantium's primary threat to its north, resulting in several wars. The two powers also enjoyed periods of peace and cooperation, most notably the alliance during the Second Arab Siege of Constantinople, where the Bulgarian army broke the siege and destroyed the Arab army, thus preventing an Arab invasion of Southeastern Europe. Byzantium had a strong cultural influence on Bulgaria, which also led to the eventual adoption of Christianity in 864. After the disintegration of the Avar Khaganate, Bulgaria expanded its territory northwest to the Pannonian Plain. Later the Bulgarians confronted the advance of the Pechenegs and Cumans, and achieved a decisive victory over the Magyars, forcing them to settle permanently in Pannonia.

The ruling Bulgars and other non-Slavic tribes in the empire gradually mixed and adopted the prevailing Slavic language, thus gradually forming the Bulgarian nation from the 7th to the 10th century. From the 10th century, the demonym Bulgarian gained prevalence and became a permanent designation for the local population, both in literature and in common parlance. The development of Old Church Slavonic prevented the assimilation of the South Slavs into neighbouring cultures, and helped to create a distinct Bulgarian identity.

After the adoption of Christianity, Bulgaria became the foremost cultural and spiritual centre of Slavic Europe. Bulgaria's position as a leading cultural power was further strengthened by the adoption of the Glagolitic alphabet and the invention of the Early Cyrillic alphabet in the capital Preslav. The literature produced in Old Church Slavonic soon began to spread north, leading to Old Church Slavonic becoming the lingua franca of much of Eastern Europe. In 927, the fully independent Bulgarian Patriarchate was officially recognized.

During the late 9th and early 10th centuries, Simeon I achieved a string of victories over the Byzantines. Thereafter, he was recognized by the title tsar (caesar), and proceeded to expand the empire to its greatest territorial extent. After the annihilation of the Byzantine army in the Battle of Anchialus in 917, the Bulgarians laid siege to Constantinople in 923 and 924. The siege failed however, and the Bulgars were forced to retreat. The Bulgarians suffered a brutal invasion by Sviatoslav I Igorevich, the Grand-Prince of the Kievan Rus, between 967 and 969, resulting in the empire becoming a vassal of the Rus. However, Sviatoslav was killed in 972, allowing the empire to briefly recover, although it was unable to reclaim the lost territories north of the Danube, in Thrace and Southern Macedonia. Their old rivals, the Byzantines, eventually recovered, and in 1014, under Basil II "the Bulgar Slayer", a crushing defeat was inflicted on the Bulgarians at the Battle of Kleidion, with Basil famously ordering the 15,000 Bulgarian prisoners to be blinded, with every 100th soldier spared one eye to guide the rest back home, forcing their families to support them for the rest of their lives. By 1018, the last Bulgarian strongholds had surrendered to the Byzantine Empire, and the First Bulgarian Empire had ceased to exist. It was succeeded by the Second Bulgarian Empire in 1185.

Nomenclature The First Bulgarian Empire became known simply as Bulgaria since its recognition by the Byzantine Empire in 681. Some historians use the terms Danube Bulgaria, First Bulgarian State, or First Bulgarian Tsardom (Empire).

Between 681 and 864 the country is also called by modern historians as the Bulgarian Khanate, or the Bulgar Khaganate, from the Turkic title of khan/khagan borne by its rulers. It is often further specified as the Danube Bulgarian Khanate, or Danube Bulgar Khanate in order to differentiate it from Volga Bulgaria, which emerged from another Bulgar group.

After the country's Christianization in 864 and implementation of the Old Church Slavonic as official language in 893, its rulers adopted the imperial title Tsar, firstly in 913, thus the country is also referred to as the Tsardom of Bulgaria. In English-language sources, the country is often known as the Bulgarian Empire.

Background Balkans during the early Migration Period

Parts of the eastern Balkan Peninsula were in antiquity inhabited by the Thracians who were a group of Indo-European tribes. The whole region as far north as the Danube River was gradually incorporated into the Roman Empire by the 1st century AD. The decline of the Roman Empire after the 3rd century AD and the continuous invasions of Goths and Huns left much of the region devastated, depopulated and in economic decline by the 5th century. The surviving eastern half of the Roman Empire, called by later historians the Byzantine Empire, could not exercise effective control in these territories other than in the coastal areas and certain cities in the interior. Nonetheless, it never relinquished the claim to the whole region up to the Danube. A series of administrative, legislative, military and economic reforms somewhat improved the situation but despite these reforms disorder continued in much of the Balkans. The reign of Emperor Justinian I (r.527–565) saw temporary recovery of control and reconstruction of a number of fortresses, but after his death the empire was unable to face the threat of the Slavs due to the significant reduction of revenue and manpower.

Slavic migrations to the Balkans

The Slavs, of Indo-European origin, were first mentioned in written sources to inhabit the territories to the north of the Danube in the 5th century AD, but most historians agree that they had arrived earlier. The group of Slavs that came to be known as the South Slavs was divided into Antes and Sclaveni who spoke the same language. The Slavic incursions in the Balkans increased during the second half of Justinian I's reign and while these were initially pillaging raids, large-scale settlement began in the 570s and 580s. This migration is associated with the arrival of the Avars who settled in the plains of Pannonia between the rivers Danube and Tisza in the 560s subjugating various Bulgar and Slavic tribes in the process.

Consumed in bitter wars with the Persian Sasanian Empire in the east, the Byzantines had few resources with which to confront the Slavs. The Slavs came in large numbers and the lack of political organisation made it very difficult to stop them because there was no political leader to defeat in battle and thereby force their retreat. As the wars with Persia persisted, the 610s and 620s saw a new and even larger migration wave with the Slavs penetrating further south into the Balkans, reaching Thessaly, Thrace and Peloponnese and raiding some islands in the Aegean Sea. The Byzantines held out in Salonica and a number of coastal towns, but beyond these areas the imperial authority in the Balkans disappeared.

Bulgars

The Bulgars were Turkic semi-nomadic warrior tribes that flourished in the Pontic–Caspian steppe and the Volga region during the 7th century. They became known as nomadic equestrians in the Volga-Ural region, but some researchers say that their ethnic roots can be traced to Central Asia. They spoke a form of Turkic as their main language. The Bulgars included the tribes of Onogurs, Utigurs and Kutrigurs, among others.

The first clear mention of the Bulgars in written sources dates from 480, when they served as the allies of the Byzantine Emperor Zeno (r. 474–491) against the Ostrogoths, although an obscure reference to Ziezi ex quo Vulgares, with Ziezi being an offspring of Biblical Shem, son of Noah, is in the Chronography of 354. In the 490s the Kutrigurs had moved west of the Black Sea while the Utigurs inhabited the steppes to the east of them. In the first half of the 6th century, the Bulgars occasionally raided the Byzantine Empire, but in the second half of the century the Kutrigurs were subjugated by the Avar Khaganate and the Utigurs came under the rule of the Western Turkic Khaganate.

As the power of the Western Turks faded in the 600s the Avars reasserted their domination over the Bulgars. Between 630 and 635 Khan Kubrat of the Dulo clan managed to unite the main Bulgar tribes and to declare independence from the Avars, creating a powerful confederation called Old Great Bulgaria, also known as Patria Onoguria, between the Black Sea, the Sea of Azov and the Caucasus. Kubrat, who was baptised in Constantinople in 619, concluded an alliance with the Byzantine Emperor Heraclius (r. 610–641) and the two countries remained in good relations until Kubrat's death between 650 and 665. Kubrat fought with the Khazars in the east but after his demise Old Great Bulgaria disintegrated under strong Khazar pressure in 668 and his five sons parted with their followers. The eldest Batbayan remained in his homeland as Kubrat's successor and eventually became a Khazar vassal. The second brother Kotrag migrated to the middle Volga region and founded Volga Bulgaria. The third brother Asparuh led his people west to the lower Danube. The fourth one, Kuber, initially settled in Pannonia under Avar suzerainty but revolted and moved to the region of Macedonia, while the fifth brother Alcek settled in central Italy.

History

Establishment and consolidation

The Bulgars of Asparuh moved westwards to what is now Bessarabia, subdued the territories to the north of the Danube in modern Romania, and established themselves in the Danube Delta. In the 670s they crossed the Danube into Scythia Minor, nominally a Byzantine province, whose steppe grasslands and pastures were important for the large herd stocks of the Bulgars in addition to the grazing grounds to the west of the Dniester River already under their control. In 680 the Byzantine Emperor Constantine IV (r.668–685), having recently defeated the Arabs, led an expedition at the head of a huge army and fleet to drive off the Bulgars but suffered a disastrous defeat at the hands of Asparuh at Onglos, a swampy region in or around the Danube Delta where the Bulgars had set a fortified camp. The Bulgars advanced south, crossed the Balkan Mountains and invaded Thrace. In 681, the Byzantines were compelled to sign a humiliating peace treaty, forcing them to acknowledge Bulgaria as an independent state, to cede the territories to the north of the Balkan Mountains and to pay an annual tribute. In his universal chronicle the Western European author Sigebert of Gembloux remarked that the Bulgarian state was established in 680."Chronica by Sigebert of Gembloux" in LIBI, vol.III, Bulgarian Academy of Sciences, Sofia, p. 42 This was the first state that the empire recognised in the Balkans and the first time it legally surrendered claims to part of its Balkan dominions. The Byzantine chronicler Theophanes the Confessor wrote of the treaty: