Kardzhali Province is a province of southern Bulgaria, neighbouring Greece with the Greek regional units of Xanthi, Rhodope, and Evros to the south and east. It is 3209.1 km2 in area. Its main city is Kardzhali.

Rhodope is one of the regional units of Greece. It is part of the region of East Macedonia and Thrace. Its name is derived from the Rhodope Mountains, which cover the northern part of its territory. Together with the regional units Evros and Xanthi, it forms the geographical region of Western Thrace. The capital of the prefecture is the city of Komotini. The second largest town is Sapes. Most of the Muslims of Thrace, the only officially recognized minority in Greece, are settled in this area, where they form around half of the regional unit's population.