Kingdom of Essex

The Kingdom of the East Saxons (), was also called the Kingdom of Essex. It was one of the seven kingdoms of the Anglo-Saxon Heptarchy. Essex was founded in the 6th century. The kingdom of Essex covered the area of the modern English counties of Essex, Hertfordshire, Middlesex and (for a short while) Kent. Kings of Essex frequently found themselves under the control of other Anglo-Saxon overlords. The territory of the East Saxons included the two Roman provincial capitals of Colchester and, for a time, London. In the Tribal Hidage the East Saxons were listed at 7,000 hides. 
History.
When they arrived in England the Saxons, like the Angles, Jutes and Frisians, were Pagans. After the Saxons gained control of Kent they set themselves up in the territory of Essex. The first attempts to convert the East Saxons to Christianity came in 604 with the arrival of Bishop (later Saint) Mellitus in London. Athelberht (King of Kent was the overlord of southern England and helped in the conversion of King Saebert of Essex. Athelberht built and endowed St. Pauls in London, where St. Paul’s Cathedral now stands. After the death of Saebert in 616, Mellitus was driven out and the kingdom reverted to paganism. King Oswi of Northumbria convinced King Sigebert of Essex to become Christian. Sigebert then invited Chad to become Bishop of London. By 874 the Great Heathen Army held much of Essex. They established bases from which they attacked other parts of England. In 825 the kingdom of the East Saxons became part of Wessex.