This thesis is a study on the use of Phoenician language for the monumental inscriptions which were set up in Plain Cilicia, and dated to the mid 8th c. BC. This thesis aims to assess the hypothesis that Phoenician, as the "trade language" of the eastern Mediterranean and the ancient Near East, became the lingua franca of the period, for the settlements in Plain Cilicia. In order to follow this hypothesis, the political structure and trade network of the period are presented. On the one hand, by proposing what motivated the local rulers in using Phoenician as the second written language, and on the other hand, based on the analysis of the archaeological and historical evidence, this thesis also questions the interest and the presence of the Phoenicians in Cilicia during the Middle Iron Age.