The Asen dynasty ruled the Second Bulgarian Empire between 1187 and 1280. The name of the dynasty suggests a barbaric, most likely Cuman origin, a likely explanation as historical sources from the 10th and the 11th century quote that a large number of barbarians (Petchenegs, Cumans and Uzes) settled in present-day northern Bulgaria and mixed with the local Bulgarian Slavs. Romanian historians, on the other hand, usually argue that the Asen dynasty was Vlach by origin. Rulers from the dynasty, for example TsarKaloyan, have been called 'Kings of Bulgarians and Vlachs' as Wallachia was part of the territory which they ruled over and most of the Bulgarian tsars from that dynasty have titled themselves 'Kings of Bulgaria and Wallachia'.
The nickname of Ivan Asen I, "Belgun" and the name of the dynasty are clearly of Turkic (most likely Cuman origin), hence some historians have described the dynasty to be of Cuman or of mixed, Cuman-Bulgarian, stock.
"Asen" is close to the Ashina clan of Eurasian rulers.
Earlier rulers from the Asen dynasty (particularly Kaloyan) referred to themselves as "Emperors of Bulgarians and Vlachs".