Vortigern and the so called 'Anglo-Saxon Invasion'
The Goths started attacking Rome in about 238AD. Gradually the so-called barbarian tribes wore down the Empire over the next 150 years or so. In about 400 AD, the Western Goths (Visigoths) invaded Spain and Italy and blockaded Rome with the aim of securing a safe homeland. After several broken truces the Christian Visigoth leader Alaric finally entered Rome on August 24th 410. This caused Rome to recall her legions from Britain, stating that Britain should 'look to its own defence'.
Moving slightly away from Arthurian matters, was there ever a King or warlord called Vortigern? If so, where was his sphere of influence? Some people place him as King of the Pagenses of Powys and Gloucestershire. Others state his kingdom as being more centralised in Britain. Did he actually invite saxon mercenaries (fedoerati) to these isles in his struggles against the Picts and Scots (Irish) in Northern Britain. How many Saxons arrived and over what time period? If the Saxons invaded in large numbers where are the battlefields and signs of upheaval in the archaeogical record?
The very fact that after the withdrawal of the majority of the Romans in the early fifth century, there is so little known makes the subject so interesting. See these opposing views in Michael Wood's In Search Of The Dark Ages and Dr. Francis Pryor's Britain BC: Life in Britain and Ireland Before the Romans.
It is a strange fact that we know more about Boudica and her Iceni as they rebelled against the Romans in AD60/61 than we do of matters some 400 years later. The reason for this is that we have no written records of the 'state of the nation' between the fifth and ninth centuries. The British way of recording results was by story telling and word of mouth. Although readers may refer to the writings of Gildas (c.540) and Bede (c.730) during these so called Dark Ages, how much creedence should we give them? Are these enlightened insights to the actual facts and events of the time, or the authors personal understanding of events that may have happened up to 300 years previously, in the case of Bede. More worrying to the researcher, is the fact that either or both historians may have been writing as clients of the leaders of the time - an early sort of propaganda.
In these days of almost reporting of news events and data retrieval, backed up by visual proof, it may be hard to understand that the 'true' history of Britain has become confused, with parts ost and other bits added long after the event - surely we all understand the concept of 'chinese whispers'.
Current research seems to indicate that the so called 'Celtic' and 'Saxon' invasion of Britain never actually happened. See The Atlantic Celts: Ancient People or Modern Invention? by Simon James and Britain AD: A Quest for Arthur, England and the Anglo-Saxons by reknowned archaeologist Dr. Francis Pryor. Theories now support the gradual change of culture by 'evolution rather than revolution' (invasion). Where are all the battlefields for any such mass invasions? What arachaeology supports the invasion theory? Concepts and new ways of working, farming, living and worshipping can be absorbed without the need for an influx of thousands of people from overseas. An archaeologist of the future would not think that Britain had been invaded by the the Japanese/Chinese/Koreans if he unearthed artifacts bearing their brandnames.