century, and it was one of the Anglo-Saxon heptarchy kingdoms as defined in the 12th century writings of Henry of Huntingdon. East Anglia has been cited by a number of scholars as being a region where settlement of continental Germanic speakers was particularly early and dense, possibly following a depopulation in the fourth century. A 2016 study found that modern East Anglians share a strong genetic affinity with Anglo-Saxon era skeletons, but differ substantially from Iron Age and Roman era ones, which are more similar to the Welsh. This was taken to support a major influence of the Anglo-Saxon migrations on the genetic makeup of East Anglia. In a 2022 study by Joscha Gretzinger et al., the populations of Norfolk and Suffolk were found to be the group with the lowest amount of Iron Age/Roman period British Isles-related ancestry, with only about 11-17.5% of their ancestry being derived from that group, while having one of the highest amounts of Continental North European (43.8-50.7%), and the highest amount of Continental West European (32.2-43.1%) ancestry in all of England. East Anglia was the most powerful of the Anglo-Saxon kingdoms of England for a brief period following a victory over the rival kingdom of Northumbria around 616, and its King Rædwald was Bretwalda (overlord of the Anglo-Saxon kingdoms). However, this did not last; the Mercians defeated it twice over the next 40 years, and East Anglia continued to weaken in relation to the other kingdoms. Offa of Mercia finally had king Æthelberht killed in 794 and took control of the kingdom himself. Independence was temporarily restored by rebellion in 825, but the Danes killed King Edmund on 20 November 869 and captured the kingdom. Edward the Elder incorporated East Anglia into the Kingdom of England, and it later became an earldom. Parts of East Anglia remained marshland until the 17th century drainage of the Fens, despite some earlier engineering work during the Roman occupation. The alluvial land was converted into wide swaths of productive arable land by a series of systematic drainage projects, mainly using drains and river diversions along the lines of Dutch practice. In the 1630s, thousands of Puritan families from East Anglia emigrated to New England in America, taking much East Anglian culture with them that can still be traced today. East Anglia based much of its earnings on wool, textiles, and arable farming and was a rich area of