This thesis concerns Bernicia and the transition from a Roman-dominated frontier zone at the beginning of the 5th century to an Anglian kingdom by the early 7th century. This is a period of great change and complexity where the current state of knowledge is limited and unsatisfactory. There is considerable scope for new research to contribute towards knowledge and understanding of this difficult area of transition. To achieve this aim, an interdisciplinary approach is adopted here that maximises existing evidential sources but focuses particularly on place-names, something that has not been done before.