Book excerpt: The German Ocean examines archaeological and historical evidence for the development of economies and societies around the North Sea from the beginning of the twelfth century until the mid sixteenth century. It draws in material from Scandinavia to Normandy and from Scotland to the Thames estuary. While largely concerned with the North Sea littoral, when necessary it takes account of adjacent areas such as the Baltic or inland hinterlands. The North Sea is often perceived as a great divide, divorcing the British Isles from continental Europe. In cultural terms, however, it has always acted more as a lake, supporting communities around its fringes which have frequently had much in common. This is especially true of the medieval period when trade links, fostered in the two centuries prior to 1100, expanded in the 12th and 13th centuries to ensure the development of maritime societies whose material culture was often more remarkable for its similarity across distance than for its diversity. Geography, access to raw materials and political expediency could nevertheless combine to provide distinctive regional variations. Economies developed more rapidly in some areas than others; local solutions to problems produced urban and rural environments of different aspect; the growth, and sometimes decline, of towns and ports was often dictated by local as much as wider factors. This book explores evidence for this 'diverse commonality' through the historic environment of the North Sea region with the intention that it will be of interest not only to historians and archaeologists but to those who live and work within the historic environment. This environment is a common European resource with much to contribute to a sustainable future - the book provides an archaeological contribution to the understanding of that resource.