The first national census was conducted in 1880 just after liberation from Ottoman rule. The name lists for all 19th century censuses have not been preserved. Ottoman census records for the period 1831-1872 were enumerations of males compiled not as population counts but for fiscal and military purposes. They contain the name of the head of household, male family members, ages, occupation, and property.
The Family History Library does not have census records from Bulgaria.