Boril of Bulgaria in the context of "Ivan Asen II"

Ivan Asen II, also known as John Asen II (Bulgarian: Иван Асен II, [iˈvan ɐˈsɛn ˈftɔri]; 1190s – May/June 1241), was Emperor (Tsar) of Bulgaria from 1218 to 1241. He was still a child when his father Ivan Asen I – one of the founders of the Second Bulgarian Empire – was killed in 1196. His supporters tried to secure the throne for him after his uncle, Kaloyan, was murdered in 1207, but Kaloyan's other nephew, Boril, overcame them. Ivan Asen fled from Bulgaria and settled in the Rus' principalities.

Boril could never strengthen his rule which enabled Ivan Asen to muster an army and return to Bulgaria. He captured Tarnovo and blinded Boril in 1218. Initially, he supported the full communion of the Bulgarian Church with the Papacy and concluded alliances with the neighboring Catholic powers, Hungary and the Latin Empire of Constantinople. He tried to achieve the regency for the 11-year-old Latin Emperor, Baldwin II, after 1228, but the Latin aristocrats did not support Ivan Asen. He inflicted a crushing defeat on Theodore Komnenos Doukas of the Empire of Thessalonica, in the Battle of Klokotnitsa in 1230. Theodore's empire soon collapsed and Ivan Asen conquered large territories in Macedonia, Thessaly and Thrace.

Anna, known in Bulgarian historiography as Kumankata (Bulgarian: Куманката, "the Cuman [woman]") (fl. 1207), was the Empress consort of Bulgaria by marriage to Kaloyan of Bulgaria and Boril of Bulgaria.

The name Anna was the name she took when she converted to Christianity. The original name of the Cuman noblewoman who subsequently married two Tsars Emperors of Bulgaria, Kaloyan of Bulgaria and Boril of Bulgaria, is unknown. There are only two sources mentioning her, both foreign. The Byzantine historian George Akropolites claimed that after the death of Kaloyan, his sister's son Boril 'married his Scythian aunt'. From this evidence, it is not sure whether the Tsaritsa was really a Cuman, or she belonged to another tribe that could be described as Scythian. As Veselin Ignatov points out, given the strong relations between the Asen dynasty and the Cumans, her Cuman lineage is the most probable possibility, but not the only one.

Strez (Bulgarian and Macedonian: Стрез; original spelling: Стрѣзъ; fl. 1207–1214) was a medieval, semi-independent Bulgarian sebastokrator. He was a member of the Asen dynasty and a cousin or a brother of Boril of Bulgaria. A major contender for the Bulgarian throne, Strez initially opposed the ascension of his close relative Tsar Boril. He fled to Serbia, where he accepted the vassalage of Grand Prince Stefan Nemanjić, and Serbian support helped him establish himself as a largely independent ruler in a large part of the region of Macedonia. However, Strez turned against his suzerains to become a Bulgarian vassal and joined forces with his former enemy Boril against the Latins and then Serbia. Strez died amidst a major anti-Serbian campaign under unclear circumstances, sometimes described as a Serbian plot.

Alexius Slav (Bulgarian: Алексий Слав, Greek: Ἀλέξιος Σθλαῦος; fl. 1208–28) was a Bulgarian nobleman (bolyarin), a member of the Asen dynasty, and a nephew of the first three Asen brothers. He was first probably the governor of the Rhodopes domain of the Second Bulgarian Empire, and then an autocrat in these lands.

He was first mentioned as one of the nobles disputing Tsar Boril's ascension to the Bulgarian throne. He married the daughter of Latin Emperor Henry of Flanders in November 1208, leaving the Bulgarian capital of Veliko Tarnovo and establishing himself as an independent ruler over the largest part of the Rhodope Mountains. Alexius Slav became a vassal of Henry after the Bulgarian defeat near Plovdiv. Henry promised to support his aspirations for the Bulgarian throne and awarded Alexius Slav the title of despot.

The Synod of Tarnovo was a council of the Bulgarian Church, at that time in union with Rome, held at Veliko Tarnovo in 1211. Emperor (or Tsar) Boril of Bulgaria convoked it to condemn Bogomilism. The decisions of the synod were included in a document, now known as the Book of Boril.

The Book of Boril or Boril Synodic (Bulgarian: Борилов синодик) is a medieval Bulgarian book from the beginning of the 13th century.It is an important source for the history of the Bulgarian Empire.

The book was written in conjunction with the Synod of Tarnovo (1211) convoked by tsar Boril against the Bogomils in 1211. Later additions and editions were made, dated at the end of XIV c.