“A Sea of Agency” were Kotsakis’ words to describe the Neolithic Aegean. As early as the dawn of human civilization, this sea was an important natural feature of the Mediterranean region, possessing several unique characteristics that make it of considerable interest. This study combines available data and narratives on the Byzantine Aegean world in order to identify regional trends and patterns in land- and water-use as well as the nature of their interaction with environmental phenomena. By looking specifically at the geography, geomorphology, geology, climate, settlement and economy, and military role of the Aegean region from the 4th to the 15th century, it investigates the particular role and “behavior” of this region within the context of the Byzantine empire.