East Anglia is a peninsula of eastern England, one of the seven Ango-Saxon Kingdoms, and later one of the Earldoms of England after the Danish conquest. It consists of of Norfolk and Suffolk, names which possibly arose during or after Danish settlement began ("North folk [people]" and "South folk [people]".) Much of East Anglia consists of marshland and bogs, despite the construction of sea barriers during the Roman period.
The Kingdom of the East Angles, formed about the year 520 by the merging of the North and the South Folk (Angles who had settled in the former lands of the Iceni during the previous century) was one of the seven Anglo-Saxon kingdoms. For a brief period following a victory over the rival kingdom of Northumbria around the year 616, East Anglia was the most powerful of the Anglo-Saxon kingdoms of England, and its king Raedwald was Bretwalda (overlord of the Anglo-Saxons kingdoms). But this did not last: over the next forty years, East Anglia was defeated by the Mercians twice, and it continued to weaken relative to the other kingdoms until in 794, Offa of Mercia had its king Æthelberht killed and took control of the kingdom himself.
The independence of the East Anglians was restored by a successful rebellion against Mercia (825 – 827), in course of which two Mercian kings were killed attempting to crush it. On November 20, 870 the Danes killed King Edmund and took the kingdom, which they named East Anglia. The Saxons retook the area in 920, only to lose it again in 1015 – 1017, when it was conquered by Canute the Great and given as a fiefdom to Thorkell the Tall, who was made Earl of East Anglia in 1017.