The evidence for peasant movements during the middle ages is, surprisingly, still only at the collection stage. Such as it is, it is very unevenly distributed chronologically. The unevenness of the distribution does not necessarily reflect an unevenness in the incidence of these movements, of course. The survival of evidence is quite accidental for most aspects of medieval life, depending not only on the preservation of records from careless storage or deliberate destruction in the middle ages but in the subsequent centuries as well. No one would expect the survival of much evidence from the early medieval centuries, when in the first place people did not keep many written records, and when the few that were kept risked destruction in the course of havoc wreaked by invasion and internecine war. However greatly the spoliation of monasteries in England and Gaul by the Viking invaders may have been exaggerated, for instance, it did exist and was directed against the most important recordkeeping institutions then in existence.