This first volume of the work "The Turks and Byzantium" mainly examines the pre-Ottoman era in the world of the East and the Balkans, particularly following the diverse relations of the Byzantine Empire, during the 10th-13th centuries, with the Turkic-speaking tribes of the East and of the Balkans - specifically with the common racial ancestors of the Turkic peoples, the Oghuz (. . .) as well as the Patzinaks (Pechenegs), the Uzuz, the Ko(y)mans, the Karakhanids (Ilekhanids), the Kara Hittai, the Seljuks , the Zengids, the Danismendids, the Artukids and the Turkoman nomads, with special reference to the Christianized Turkopoulos mercenaries. The general chronological framework of Byzantine-Turkish relations, i.e. the period 4th - 15th century, will be completed in a second volume.