While it may seem a peculiar place to start, the separation of the British Isles from the European mainland by water at the end of the last glacial period of the Ice Age, some 8,500 years ago, is perhaps the fundamental event which has governed relationships between the inhabitants of those islands and those of the European mainland ever since. The North Sea acted then, as now, as a natural barrier to direct and immediate contact, but one which with a little effort and some maritime technology could be quickly and easily traversed. Thus, varying amounts of contact were kept up and the inhabitants of the British Isles could opt into European affairs across this permeable barrier when they wished to, or remain relatively insular. The problem for the medieval historian is that the evidence of many of the points of contact across this natural barrier is typically sparse and brief, often poorly recorded and preserved, and of a form which rarely lends itself to thorough study. The student seeking to know something of this must be content with meagre fare, albeit usually fascinating, and more often than not leading to less than definitive conclusions.

One crucial distinction that must be made here is that of a distinction of distance, that is between England's close-range contacts with her immediate neighbours: Normandy, northern France, Flanders and northern Germany, but also under the Anglo-Danish kings Denmark and the coastline to its east, and its more distant contacts, such as Rome or the imperial court. England from its vantage point on the north-western edge of the landmass of Europe, mundanely interacted with its closest neighbours as well as sent its inhabitants on more special missions to those nearby countries. More distant contacts where traceable often involve individual travel and pilgrimage, as well as missions sent by secular or ecclesiastical elites. Such forms of distant contact involve far fewer individuals, but can provide the most startling revelations; and in the least contacts with cultural hubs such as Rome or the imperial court may indicate interaction with the core of the leadership of mainland Europe. It should be noted that some regions such as the northernmost parts of the Empire, such as Lotharingia and the Upper Rhine, seem to partly sit in both categories, as neighbours of England involved in local trade as well as points of conduit to imperial Germany and beyond.