In the past, the lands along the banks of the Rezovska River belonged to Bulgaria, and later they belonged to the Ottoman Empire.Today the river is shared between Bulgaria and neighboring Turkey.The twists and turns in history are perhaps best illustrated by the bridge between the two banks of the river south of the town of Malko Tarnovo.This bridge will be discussed again a little later.The Rezovska River has been chosen as the southern border of the Republic of Bulgaria with the Republic of Turkey.The river is formed by the confluence of the Paspalderesi River and the Velika River on the territory of Turkey.It then flows in a northerly direction for about 3 km and reaches the Bulgarian border 8 km south of the city of Malko Tarnovo at the mouth of its left tributary, the Delievska River.From here to its mouth, the river serves as the border between the two countries.The length of the river is approximately 112 km.It flows into the Black Sea at the Bulgarian village of Rezovo, which is also the southernmost point of the Bulgarian Black Sea coast.There are different versions about the origin of the name of the river.According to one of them, it is named after King Rezos (in some sources he is referred to as Rez).He is one of the most famous Thracian kings.Ancient Greek poet Homer (8th century BC) describes him in the Iliad as the most powerful among the Thracian allies of Troy.Much later, Euripides (5th century BC) in his tragedy "Rezos" describes him as the ruler of the Thracian tribe of Edoni, also called Edonians or Edonids, who inhabited Southwestern Thrace along the lower reaches of the Struma River to its mouth.In the east, their lands reached the Nestos River (today Mesta River), which served as a natural border with the lands of True Thrace.
Dimcho Zahariev (Sun,) studied this question.