The House of Asen, also Asen dynasty or the Asenids (Bulgarian: Асеневци, romanized: Asenevtsi), founded and ruled a medieval Bulgarian state, called in modern historiography the Second Bulgarian Empire, between 1185 and 1280.
The Asen dynasty rose as the leaders of Bulgaria after a rebellion against the Byzantine Empire at the turn of the year 1185/1186 caused by the increase in the Imperial taxes.
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.
The Uprising of Asen and Peter (Bulgarian: Въстание на Асен и Петър) was a revolt of Bulgarians and Vlachs living in Moesia and the Balkan Mountains, then the theme of Paristrion of the Byzantine Empire, caused by a tax increase. It began on 26 October 1185, the feast day of St. Demetrius of Thessaloniki, and ended with the restoration of Bulgaria with the creation of the Second Bulgarian Empire, ruled by the Asen dynasty.
Isaac II Angelus, in order to raise money for his wedding with the daughter of King Béla III of Hungary, levied a new tax which fell heavily on the population of the Haemus Mountains. They sent two leaders (Peter and Asen) to negotiate with the emperor at Kypsella (now İpsala) in Thrace. They asked to be added to the roll of the Byzantine army and to be granted land near Haemus to provide the monetary income needed to pay the tax. This was refused, and Peter and Asen were treated roughly. Their response was to threaten revolt.
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.
Michael Asen III (Bulgarian: Михаил Асен III, romanized: Mihail Asen III), commonly known as Michael Shishman (Bulgarian: Михаил Шишман, romanized: Mihail Shishman), ruled as tsar of Bulgaria from 1323 to 1330. The exact year of his birth is unknown but it was between 1280 and 1292. He was the founder of the last ruling dynasty of the Second Bulgarian Empire, the Shishman dynasty. After he was crowned, however, Michael used the name Asen to emphasize his connection with the Asen dynasty, the first one to rule over the Second Empire.
An energetic and ambitious ruler, Michael Shishman led an aggressive but opportunistic and inconsistent foreign policy against the Byzantine Empire and the Kingdom of Serbia, which ended in the disastrous Battle of Velbazhd that claimed his own life. He was the last medieval Bulgarian ruler who aimed at military and political hegemony of the Bulgarian Empire over the Balkans and the last one who attempted to seize Constantinople. He was succeeded by his son Ivan Stephen and later by his nephew Ivan Alexander, who reversed Michael Shishman's policy by forming an alliance with Serbia.