The monograph is dedicated to Syria and Cilicia during the era of the Crusades (XI-XIII centuries) - as a unique and little-studied center of contact between the Latin West and the Byzantine East. For the first time, an attempt was made to unite, within the framework of a single study, the history of church, military, diplomatic, economic and cultural contacts between Latins and Orthodox Christians (Romans, Melkites, Georgians, Chalcedonian Armenians) associated with Antioch, Edessa, Cilician and North Syrian states " Overseas Land" (the Principality of Antioch, the County of Edessa, the County of Tripoli, the Kingdom of Cilician Armenia). This book is a fairly diverse study, including a detailed history of the Roman and Franco-Norman military campaigns in Syria and Cilicia, descriptions of the cities, churches and monasteries of the Levant, a review and analysis of various forms of contact between Latin and Byzantine Christians in the sphere of church, political and cultural life of the Middle Ages Syria and the eastern Mediterranean. The author relies on a wide range of sources - from medieval chronicles, messages and charters, to numerous monographs and publications of Western and domestic researchers of the 19th–21st centuries.