<P> Demographic Model: This model suggests that Scandinavia experienced a population boom just before the Viking Age began . The agricultural capabilities of the land were not enough to keep up with the increasing population . As a result, many Scandinavians found themselves with no property and no status . To remedy this, these landless men took to piracy to obtain material wealth . The population continued to grow, and the pirates looked further and further beyond the borders of the Baltic, and eventually into all of Europe . </P> <P> Economic Model: The Economic Model states that the Viking Age was the result of growing urbanism and trade throughout mainland Europe . As the Islamic world grew, so did its trade routes, and the wealth which moved along them was pushed further and further north . In Western Europe, proto - urban centres such as the - wich town of Anglo - Saxon England began to boom during the prosperous era known as the "Long Eighth Century". The Scandinavians, like many other Europeans, were drawn to these wealthier "urban" centres, which soon became frequent targets of Viking raids . The connection of the Scandinavians to larger and richer trade networks lured the Vikings into Western Europe, and soon the rest of Europe and parts of the Middle East . In England hoards of Viking silver such as the Cuerdale Hoard and the Vale of York Hoard, offer good insight to this phenomenon . </P> <P> Ideological Model: This era coincided with the Medieval Warm Period (800--1300) and stopped with the start of the Little Ice Age (about 1250--1850). The start of the Viking Age, with the sack of Lindisfarne, also coincided with Charlemagne's Saxon Wars, or Christian wars with pagans in Saxony . Historians Rudolf Simek and Bruno Dumézil theorise that the Viking attacks may have been in response to the spread of Christianity among pagan peoples . Professor Rudolf Simek believes that "it is not a coincidence if the early Viking activity occurred during the reign of Charlemagne". Because of the penetration of Christianity in Scandinavia, serious conflict divided Norway for almost a century . </P> <P> Political Model: There are two main components to the Political Model . In the first case, there is the external "Pull" factor . The Pull factor suggests that the weak political bodies of Britain and Western Europe made for an attractive target for Viking raiders . The reasons for these weaknesses vary, but generally can be simplified into decentralized polities, or religious sites . As a result, Viking raiders found it easy to sack and then retreat from these areas which were thus frequently raided . In the second case, there is the internal "Push" factor . The Push factor coincides with a period just before the Viking Age in which Scandinavia was undergoing a mass centralization of power in the modern day countries of Denmark, Sweden, and especially Norway . This centralization of power forced hundreds of chieftains from their lands, which were slowly being eaten up by the kings and dynasties that began to emerge . As a result, many of these chiefs sought refuge elsewhere, and began harrying the coasts of the British Isles and Western Europe . </P>

How many years did the vikings raid england