The Tundzha is a river in Bulgaria and Turkey and the most significant tributary of the Maritsa, emptying into it on Turkish territory near Edirne. The river originates in the central parts of Stara Planina north of Kalofer, initially flowing east and then making a sharp turn to the south before Yambol, in which direction it flows until it reaches the Maritsa. The Tu…The Tundzha is a river in Bulgaria and Turkey and the most significant tributary of the Maritsa, emptying into it on Turkish territory near Edirne. The river originates in the central parts of Stara Planina north of Kalofer, initially flowing east and then making a sharp turn to the south before Yambol, in which direction it flows until it reaches the Maritsa. The Tundzha's length is about 365 km, of which 328 km is on Bulgarian territory. It has about 50 tributaries, the more important of which are Mochuritsa, Popovska, and Sinapovska.