С. Раковски". София, 2005 г. According to Raymond Detrez, the Iranian theory is rooted in the periods of anti-Turkish sentiment in Bulgaria and is ideologically motivated. Since 1989, anti-Turkish rhetoric is now reflected in the theories that challenge the thesis of the proto-Bulgars' Turkic origin. Alongside the Iranian or Aryan theory, there appeared arguments favoring an autochthonous origin. Ethnicity Due to the lack of definitive evidence, modern scholarship uses an ethnogenesis approach in explaining the Bulgars origin. More recent theories view the nomadic confederacies, such as the Bulgars, as the formation of several different cultural, political and linguistic entities that could dissolve as quickly as they formed, entailing a process of ethnogenesis. According to Walter Pohl, the existential fate of the tribes and their confederations depended on their ability to adapt to an environment going through rapid changes, and to give this adaptation a credible meaning rooted in tradition and ritual. Slavs and Bulgars succeeded because their form of organization proved as stable and as flexible as necessary, while the Pannonian Avars failed in the end because their model could not respond to new conditions. Pohl wrote that members of society's lower strata did not feel themselves to be part of any large-scale ethnic group; the only distinct classes were within the armies and the ruling elite. Recent studies consider ethnonyms closely related with warrior elites who ruled over a variety of heterogeneous groups. The groups adopted new ideology and name as political designation, while the elites claimed right to rule and royal descent through origin myths. When the Turkic tribes began to enter into the Pontic–Caspian steppe in the Post-Hunnic era, or as early as the 2nd century AD, their confederations incorporated an array of ethnic groups of newly joined Turkic, Caucasian, Iranian, and Finnic peoples. During their Western Eurasian migrations to the Balkans, they also came into contact with Armenian, Semitic, Slavic, Thracian and Anatolian Greek among other populations. From the 6th to 8th centuries, distinctive Bulgar monuments of the Sivashovka type were built upon ruins of the late Sarmatian culture of the 2nd to 4th centuries AD, and the 6th century Penkovka culture of the Antes and Slavs. Early medieval Saltovo-Mayaki (an Alanic-based culture) settlements in the Crimea since the 8th century were destroyed by the Pechengs during the 10th century. Although the older Iranian tribes were enveloped by the widespread Turkic migration into the Pontic–Caspian steppe,