In medieval sources the name of the contemporary city of Strumica is found in two versions: Strumica or Tiberiupolis. While the Slavic toponym has been well authenticated in the sources, the appearance and the use of the Tiberiupolis as the synonym of Strumica has remained a puzzle for researchers. In her paper the author attempts to discuss the existence of the toponym Tiberiupolis which was first encountered in written sources of the 11th century. Both the Slavic and the Byzantine version of the city name have somewhat been connected with the cult of the Fifteen Holy Martyrs spread and observed in the Strumica region. Regardless of whether Strumica was ever called Tiberiupolis, the city and the episcopacy in several instances, only in local (church) sources, appeared under this name between the 11th and 14th century. The fact that Tiberiupolis was used by the church allows one to assume that due to the symbolism the name entails, best expressed through the cult of the Fifteen Holy Martyrs from Tiberiupolis, it was significant to the local clergy. By supporting and perpetuating the memory of the deeds and suffering of the martyrs, the church performed its mission of spreading Christian values in a predominantly Slavic region as Strumica and its surroundings in the Middle Ages. .
