In 705, Ktenia became part of the First Bulgarian Empire when the Zagore area was ceded to Tervel by the Byzantine Empire. When the Bulgarian Empire was reestablished at the end of the 12th century, Ktenia was once again under Bulgarian control until it was conquered by the Byzantines during the Uprising of Ivaylo (1277–1280). The fortress was recovered by Bulgaria after a successful war by emperor Theodore Svetoslav (r. 1300–1321) in 1304. However, it was lost during the period of uncertainty after the premature death of his son George II Terter (r. 1321–1322). Ktenia was quickly recaptured by the new emperor Michael Shishman (r. 1323–1330) in 1324. After another brief Byzantine occupation between 1330 and 1332, it was once again captured by the Bulgarians in the aftermath of the Battle of Rusokastro on 18 July 1332.