Its range includes most of the Central Rhodopes, i.e. the region of Smolyan.
To the south, the Smolyan dialect crosses the Greek-Bulgarian border and is spoken by much of the Muslim Bulgarian (Pomak) population in Western Thrace.
As a result of the rugged mountainous terrain and the century-long isolation of the region from the rest of the country, the Smolyan dialect is the most idiosyncratic of all Bulgarian dialects and is not readily understandable even for its immediate neighbours.
For other phonological and morphological characteristics typical for all Rup or Rhodopean dialects, cf.
Стойков, Стойко: Българска диалектология, Акад.