It is named after its administrative centre - the town of Belogradchik.
The very archive is currently stored in several cities – Sofia, Stara Zagora and Belogradchik.
The range of the dialects includes most of northwestern Bulgaria, to the west of the line between Nikopol, Pleven and Mezdra and to the north of the line between Vratsa and Belogradchik.
On Bulgarian territory, the Transitional dialects occupy a narrow strip of land along the Bulgarian border with Serbia, including the regions of Tran, Breznik, Godech and Belogradchik.
Jérôme-Adolphe Blanqui mentions it as Chupren in the description of his journey from Belogradchik to Niš in 1841.
It is located in northwestern Bulgaria, between the villages of Rabisha and Tolovitsa in Belogradchik municipality, Vidin Province.