History The Bulgarian population was formed as a result of the merging of the three ethnic groups - Thracians, Slavs and Old Bulgarians. Before 1913 the area of Mesta/Nestos catchment as well as Bulgaria was about 5 centuries under Turkish invasion. It was liberated in 1913. The northern part of the catchment was incorporated in the Bulgarian territory while the south part in Greek. Until 1944, the region set up gradually its identity in Tsarist Bulgaria. Between 1944 and 1989 the region had been intensively developed and drastic changes occurred in social and industrial level. This period is known as totalitarian regime in Republic of Bulgaria and is the most successful concerning social and cultural advance. The population reaches its maximum. New towns as Bansko, Yakoruda, Belitza and Hadjidimovo were laid out. Since 1989 the reference area and the whole country are in a transitional period from totalitarian to market economy. During the ancient years, the Bisaltes were living in the Greek side of the catchment, one of the many Thracians tribes. Alexander the Great conquered Thrace and the area Hellenised. In the years to come the territory was invaded by many nations such as the Romans, Goths, Bulgarians, Slavs and many others. Finally, in 14th century the region was occupied by the Turkish army, until 1923. Since then the catchment is incorporated in Greece.