The mediaeval town of Larisa and its immediate vicinity -the most important part of Thessaly- in central Greece have been generally viewed as one of the most remote and underdeveloped areas within the Byzantine Empire. By the examination of the sources under a new light and the exploitation of new archaeological evidence the present thesis challenges this traditional view and attempts to highlight the key role which Larisa played as one of the most prominent administrative and ecclesiastical centres in Greece. Chapter One deals with the invasions of the Slavs in the Thessalian territory during the 6th-7th centuries, their subsequent settlements and their final absorption in the Byzantine state through their hellenization and Christianisatio...