Anglo-Saxon Northumbria is renowned for producing scholars of the eminence of Bede and Alcuin and saints of the stature of Cuthbert and Oswald. But despite its enormous cultural and political impact on the course of early English history, only a relatively small amount of documentary material has survived, scattered through five different archives. This book constitutes the first edition of all Anglo-Saxon charters surviving in archives north of the River Humber, a body of material previously neglected. It provides edited texts, together with detailed analysis and commentary, for twenty-one documents which have been preserved in the ecclesiastical archives of York, Beverley, Ripon and Durham, and also a unique survival from Lowther Castle. These commentaries also provide translations and elucidations of each Old English boundary clause and assessments regarding each document's authenticity. The charters themselves are preceded by comprehensive historical introductions which not only provide up-to-date historical accounts of each religious house, but also give an overview of the evolution of each ecclesiastical archive (Lowther Castle is treated slightly differently). In bringing all of this material together for the first time, this book encourages comparisons between the types of charter used in different parts of Northumbria, which in turn allows a better understanding of the complex political and ecclesiastical situation throughout the kingdom.