Krum in the context of "Bulgars"

Sofia is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain, in the western part of the country. The city is built west of the Iskar river and has many mineral springs, such as the Sofia Central Mineral Baths. It has a humid continental climate.

Known as Serdica in antiquity, Sofia has been an area of human habitation since at least 7000 BC. The recorded history of the city begins with the attestation of the conquest of Serdica by the Roman Republic in 29 BC from the Celtic tribe Serdi. During the decline of the Roman Empire, the city was raided by Huns, Visigoths, Avars, and Slavs. In 809, Serdica was incorporated into the First Bulgarian Empire by Khan Krum and became known as Sredets. In 1018, the Byzantines ended Bulgarian rule until 1194, when it was reincorporated by the Second Bulgarian Empire. Sredets became a major administrative, economic, cultural and literary hub until its conquest by the Ottomans in 1382. From 1530 to 1836, Sofia was the regional capital of Rumelia Eyalet, the Ottoman Empire's largest and most important province. Bulgarian rule was restored in 1878. Sofia was selected as the capital of the Third Bulgarian State in the next year, ushering a period of intense demographic and economic growth.

Krum's dynasty (Bulgarian: Крумова династия) was the royal and later imperial family founded by the Khan of Bulgaria Krum (r. 803–814), producing the monarchs of First Bulgarian Empire between 803 and 991. During this period Bulgaria adopted Christianity, reached its greatest territorial extent and triggered a golden age of culture and literature. Under the patronage of these monarchs Bulgaria became the birthplace of the Cyrillic alphabet; Old Bulgarian became the lingua franca of much of Eastern Europe and it came to be known as Old Church Slavonic. As a result of the victory in the Byzantine–Bulgarian war of 913–927 the Byzantine Empire recognized the imperial title of the Bulgarian rulers and the Bulgarian Orthodox Church as an independent Patriarchate.

The last representative of the dynasty, Tsar Roman (r. 977–991), was succeeded by Tsar Samuel (r. 997–1014) of the Cometopuli dynasty, upon the former's death in Byzantine captivity in 997, after spending six years in prison. Samuel had made the last member of Krum's dynasty a nominal head of state in 977, in order to avoid conflict.

Bulgarian Battle of Versinikia (Bulgarian: Битката при Версиникия; Greek: Μάχη της Βερσινικίας) was a battle fought in 813 AD between the Byzantine Empire and the Bulgarian Empire, near the city of Adrianople (Edirne), in modern-day Turkey.

The Bulgarian army, led by Krum of Bulgaria, defeated the Byzantine forces. Following this defeat, Michael I Rangabe abdicated, with Leo V the Armenian taking the Byzantine throne. The battle further strengthened Bulgarian control in the region after their victory over Nikephoros I two years earlier. After the battle, the Bulgarians controlled the whole region of Eastern Thrace (until the Byzantine–Bulgarian Treaty of 815), with the exception of a few castles that remained in Byzantine control. Krum died on 13 April 814, but his muster of "5,000 iron-plated wagons [ . . . ] to carry the siege equipment" alarmed the Byzantine court to such an effect that they asked for the aid of the Carolingian Emperor Louis the Pious. These large-scale military preparations were Krum's attempt to avenge his failure at the Second Bulgarian Siege of Constantinople one year prior.

Leo V the Armenian (Greek: Λέων ὁ Ἀρμένιος, Léōn ho Arménios; c. 775 – 25 December 820) was the Byzantine emperor from 813 to 820. He is chiefly remembered for ending the decade-long war with the Bulgars, as well as initiating the second period of Byzantine iconoclasm.

A senior general of Armenian origin, Leo distinguished himself under Nikephoros I and Michael I Rhangabe, eventually becoming the stratēgos of the Anatolic Theme. Taking advantage of Michael's defeat at the Battle of Versinikia, he forced the emperor to abdicate in his favour. He was able to withhold the blockade of Constantinople by Krum of Bulgaria and, after Krum's death, concluded a 30-year peace with his successor Omurtag.

The siege of Constantinople in 813 (Bulgarian: Обсада на Константинопол) by Khan Krum (Bulgarian: Крум) was a failed attempt to take the city during the Byzantine–Bulgarian wars.

The Battle of Pliska or Battle of Vărbitsa Pass was a series of battles between troops, gathered from all parts of the Byzantine Empire, led by the Emperor Nicephorus I, and the First Bulgarian Empire, governed by Khan Krum. The Byzantines plundered and burned the Bulgar capital Pliska which gave time for the Bulgarians to block passes in the Balkan Mountains that served as exits out of Bulgaria. The final battle took place on 26 July 811, in some of the passes in the eastern part of the Balkans, most probably the Vărbitsa Pass. There, the Bulgarians used the tactics of ambush and surprise night attacks to effectively trap and immobilize the Byzantine army, thus annihilating almost the whole army, including the Emperor. After the battle, Krum encased the skull of Nicephorus in silver, and used it as a cup for drinking. This is one of the most documented instances of the custom of the skull cup.

The Battle of Pliska was one of the worst defeats in Byzantine history. It deterred Byzantine rulers from sending their troops north of the Balkans for more than 150 years afterwards, which increased the influence and spread of the Bulgarians to the west and south of the Balkan Peninsula, resulting in a great territorial enlargement of the First Bulgarian Empire.