How did the swineherd Ivaylo become tsar of Bulgaria?

Ivaylo, a swineherd, rose to the throne of Bulgaria during a period of significant internal instability within the Second Bulgarian Empire. Following the reign of Ivan Asen II, the Bulgarian state faced mounting pressure from Mongol invasions and severe internal unrest caused by the heavy burdens that powerful nobles placed upon the peasantry.12

In response to these conditions, a great peasant revolt broke out between 1277 and 1280. Ivaylo emerged as the leader of this uprising, which successfully challenged the existing order and allowed him to occupy the royal throne at Tŭrnovo. His rule was short-lived, however, as he was eventually defeated with the assistance of the Byzantine Empire.12