Details about Rædwald's reign are scarce, primarily because the Viking invasions of the 9th century destroyed the monasteries in East Anglia where many documents would have been kept.

A smaller ship-burial was also discovered in 1998 close to the original Sutton Hoo site, which is thought to have contained the body of his son Rægenhere, who died in battle in 616.

The historian Barbara Yorke argues that East Anglia almost certainly produced a similar range of written materials, but they were destroyed during the Viking conquest in the 9th century.

[5] The earliest and most substantial source for Rædwald is the Historia ecclesiastica gentis Anglorum (Ecclesiastical History of the English People), completed in 731 by Bede, a Northumbrian monk.

Bede placed Rædwald's reign between the advent of the Gregorian mission to Kent in 597 and the marriage and conversion of Edwin of Northumbria during 625–626.

[7][8] Rædwald is however referred to in the 8th century Vita of St Gregory the Great, written by a member of the religious community at Whitby.

[9] The Battle of the River Idle, in which Rædwald and his forces defeated the Northumbrians, is described in the 12th century Historia Anglorum, written by Henry of Huntingdon.

[15][16] The Bernician dynasty, allied by kinship to the kingdom of Wessex, gained ascendancy over Deira, forcing Edwin to live in exile in the court of Cadfan ap Iago of Gwynedd.

In 597 in the early years of Rædwald's reign Augustine of Canterbury arrived on mission from Rome, leading to the conversion of the bretwalda Æthelberht of Kent as well as Saeberht of Essex, and the establishment of new bishoprics in their kingdoms.

Bede, writing decades later, described how Ealdwulf of East Anglia, a grandson of Rædwald's brother Eni, recalled seeing the temple when he was a boy.

[32] Barbara Yorke argues that Rædwald was not willing to fully embrace Christianity because conversion via Æthelberht would have been acknowledgment of an inferior status to the Kentish king.

[35] Æthelfrith pursued Acha's exiled brother Edwin in an attempt to destroy him and ensure that the Bernician rulership of Northumbria would be unchallenged.

If, as is supposed by some, Paulinus appeared to him in the flesh, the bishop's presence at Rædwald's court would throw some light on the king's position regarding religion.

[38] Rædwald's pagan queen admonished him for acting in a manner dishonourable for a king by betraying his trust for the sake of money and wanting to sell his imperiled friend in exchange for riches.

Kirby has argued that the battle was more than a clash between two kings over the treatment of an exiled nobleman but was "part of a protracted struggle to determine the military and political leadership of the Anglian peoples" at that time.

After the death of the Christian Saebert of Essex, his three sons shared the kingdom, returning it to pagan rule, and drove out the Gregorian missionaries led by Mellitus.

It took another hundred years for the settlement to develop into a town, but its beginnings can be seen as a reflection of the personal importance of Rædwald during the period of his supremacy.

[50] His death is recorded twice by Roger of Wendover, in 599 and in 624, in a history that dates from the 13th century but appears to include earlier annals of unknown origin and reliability.

[53] Since the excavation of Mound 1 in 1939 at Sutton Hoo, near Woodbridge, Suffolk there has been speculation that the Rædwald was the person either buried or commemorated in the main chamber.

Rædwald lived at a time when eminent individuals were buried in barrows at the cemetery at Sutton Hoo three still visible large mounds overlooking the upper estuary of the River Deben.

[54] In 1939 the largest mound at Sutton Hoo was found to contain a uniquely rich Anglo-Saxon ship-burial in the centre of which was a chamber containing grave goods for a very wealthy man with items pointing to imperial claims such as consular sceptre which may have been a symbol of the office of bretwalda and gold and garnet body-equipment which employed a goldsmith at the top level in Europe which could project an image of imperial power.

[55][56] The symbolism and the wealth displayed point to the death of a person connected with the royal court, with Rupert Bruce-Mitford,[57] first positing the burial as "very likely the monument of the High King or bretwalda Rædwald".

[58] Yorke suggests that the treasures buried with the ship reflect the size of the tribute paid to Rædwald by subject kings during his period as bretwalda.

[66] Swedish cultural influence has been detected at Sutton Hoo: there are strong similarities in both the armour and the burial with Vendel Period finds from Sweden.

[67] There are also significant differences, and exact parallels with the workmanship and style of the Sutton Hoo artefacts cannot be found elsewhere; as a result the connection is generally regarded as unproven.