In history, the Anglo-Saxon period is used to refer to the period from the first Germanic incursions in the 5th century up until the Norman conquest of 1066.
For much of the Anglo-Saxon period, the territory was divided amongst competing micro-nations - whilst the term heptarchy is used for this period, it is debatable whether there were exactly seven of them for any considerable length of time. Mercia was the most powerful for much of the Dark Ages, until Danish incursions removed much of North-East England from Anglo-Saxon control. However, in the 9th century, Wessex, under a series of talented rulers culminating in Alfred the Great, established its supremacy. Eventually, all the Germanic peoples of Britain were united under Athelstan, who is often considered the first true King of England.