Pointers to the suggested pattern of settlement underlying the current theory.
Archaeology (I write as a complete non-specialist).
The archaeological evidence for the area of early settlement in the upper Thames valley begins in at least the early fifth century and comes chiefly from the Ock and Thames confluences. There is possible evidence of co-residence between British and Anglo-Saxons at Queenford Farm, Dorchester. ‘The evidence from Dorchester for co-existence between the first Anglo-Saxon generations and the first post-Roman British ones is quite impressive.’ (Blair 1994: 6) [John Blair Anglo-Saxon Oxfordshire (1994) Chapter i. p. 6.] By the second half of the fifth century the upper Thames was quite thickly settled by people whose culture came ultimately from the coastal plain of Germany and the mouth of the Weser but whose immediate affinities were with settlers in Surrey, Essex, west Kent, and Sussex. (Dickinson 1976 415–17 cited in Blair 1994:8). The Thames was the likely route for these settlers. This in itself does not imply new waves of immigrants, though it might: it could simply point to population expansion. Towards the end of the century the dispersal of peripheral sites (up the Cherwell, Thames, Windrush, and into the Cotswolds) suggests not pioneers sent out by a military commander but either peaceful co-existence or Britons who had adopted Saxon culture (Blair 1994:9).
A more marked change seems to have occurred in the first part of the sixth century. Between 500 and 600 there was great expansion. By this time there were strong Anglian settlements on the other side of the Cotswolds from the upper Thames. During 500–550 there is evidence of much greater trading links and correspondingly more coherent communities. Place name evidence, Blair suggests, points to a more warlike culture. Eventually after 600: ‘The occupants of ‘princely’ tombs must be, in degree if not in kind, a new elite controlling new resources and aware of new horizons, acquiring theire attributes of status through Europe-wide exchange systems’ (Blair 1994:33) ‘In many cultures the appearance of planned, organised and regular structures has marked a key stage in social development; around 600 the English reached that stage.’ (Ibid.)
Härke 2011 [Heinrich Härke, 2011 ‘Anglo-Saxon Immigration and Ethnogenesis’ in Medieval Archaeology 55, 1–28] identifies three types of settlement:
1. The ‘kin group’, exemplified at Berinsfield from the late 5th to early 7th centuries, whereby Germanic immigrants and their descendants lived with native Britons in the same social unit, a large household, but did not intermarry because of a status difference between the immigrants and natives.
2. The ‘warband’ model, exemplified by materials at Stretton-on-Fosse (Warwickshire) which suggest an influx of group of males who took control of community and married local women (a less frequent model).
3. The ‘elite transfer’ model, whereby a small group took over a kingdom, which entailed greater native survival (especially found in the north).
He also suggests (p. 16) that acculturation, i.e. the adoption by natives of the material culture of the dominant immigrants, was a gradual process, likely to have started early. There is no 5th-century evidence for it. The materials at Wallingford suggest that it was under way by the 6th century: this was a native enclave that used Saxon dress items in the 6th century but was recognized as ‘Welsh’ in the 7th to 8th centuries.
Some kind of two-phase settlement seems to be archaeologically discernible in East Anglia. Anglo-Saxon settlement is evidenced there early, possibly from the last few years of the fourth century (cremation urn cemeteries outside Caistor by Norwich). Already by 500 there was substantial occupation in the Norwich area, north and west Norfolk, Breckland, and the fenland margins. Then there are new arrivals in the Ipswich area in the early sixth century; there is a theory that they were from Scandinavia; they controlled East Anglia by 550. Rædwald’s reign traditionally began in 590, and he was described as overlord of southern England till 624/5. Rhineland products began to arrive after 600 evidencing North Sea trade.
Dr Caitlin R. Green writes on her website Arthuriana (referenced 22 Feb. 2016):
There is now a significant body of evidence to suggest that the former Late Roman provincial capital of Lincoln retained its centrality into the post-Roman period, becoming the focus of a British polity known as *Lindes. This polity was eventually taken over by the Anglo-Saxon immigrants to this region to become the seventh-century kingdom of Lindissi (a name that derives from *Lindes), but as a British political territory it probably survived right the way through the fifth century and at least some way into the sixth. There is, for example, a remarkable quantity of British high-status metalwork of the fifth and sixth centuries now known from Lincolnshire, and the old Roman forum at Lincoln looks to have been used as the site for a British Christian church during the fifth and sixth centuries. Most importantly, this fifth- to sixth-century British polity appears to have been able to control the Anglo-Saxon immigrants who arrived in its territory, with this control only seeming to break down after the early sixth century.
So, on the one hand, there is evidence of early settlement in most of the areas where later kingdoms emerged: 5th century or earlier in upper Thames valley; early 5th century at Mucking, etc. in Essex; 5th century between the Ouse and Cuckmere in Sussex; 450 in East Anglia around Caistor/Venta Icenorum; 5th century in Lindsey; 450 in Deira in East Yorkshire (as opposed to ?6th century in Bernicia); ?5th century in Mercia in the Trent Valley. On the other hand, the era of organized polities with traditional ruler-names (implying some kind of warrior elite), and the heightened trade contacts on which these would partly depend, seems to begin at the end of the fifth or beginning of the sixth centuries.
If we turn to the Old English historical sources, with the possible exception of Kent they all point to the sixth century for the beginnings of a new kind of organized polity. In Wessex, Cerdic (with Celtic name), rules as king of the Gewisse, i.e. probably the upper Thames valley (not Hampshire as in the Chronicle legend legitimizing the later West Saxon heartland), 519–534, seemingly founding a princely dynasty continued by Cynric 534–560, and Ceawlin 560–591. Essex is supposed to emerge as a kingdom under Æscwine or Erkenwine (c527–c587), a semi-legendary settler from ‘Old Saxony’. In Sussex, Ælle (477–514) is supposed by the Chronicle to be king and first Bretwalda; his successor Cissa is only a co-ruler in 491 and king in 514 (d. 567); after which there is a gap till Æthelwealh, floruit c660–c685. In East Anglia there are three shadowy kings Wehha, Wuffa, and Tytila, the latter assigned to the 570s, before the emergence of the great Rædwald (c616–c627). Ælla of Deira appears in 559/560 with just the patronymic Yffing. Ida (547–559) is preceded in Bernicia by the little-known Esa (c500) and Eoppa (c520). Icel, the founder of the Mercian dynasty, led his people, according to tradition, from Angel to Britain at some point from c515 or c527. He is followed by shadowy figures Cnebba and Cynewald. His great grandson Creoda (c584–c593), may have founded the royal fortress at Tamworth. In Kent, Hengest, Horsa, and Oisc are of course very early, but it is dubious whether they really imply the establishment of a fully fledged kingdom; this may be more securely suggested by their successors Octa 512/516–534/540, Eormenric, and the well-attested Æthelberht I (?560/?565–616/618). Eastern Kent seems in fact the only area that (a) was settled early, (b) had a tradition of early noble, warrior leaders, and (c) was well connected with the continent.
None of this dating is very secure, but if it can be accepted in very general terms it does seem to point to the rise (and in some cases, the arrival) of ‘aristocratic’ warrior elites, and rulers looking to continental models of kingship, in about the second decade of the sixth century. (Is it significant that the early names are all of the form root + -a or –e, and that the conventional two-element names appear only from the mid sixth century onwards?)
Looking at literary sources, the narratives in Beowulf constitute a brief and allusive summary of a number of the semi-legendary histories of the heroic or migration period (call it whichever you like). Scholars have assigned a rough chronological framework to the kings and heroes celebrated in these histories. The time span is roughly from the mid fourth to the early sixth century. Ermanaric, whose death is recorded as 376, and Offa of Angel, also fourth century, come at the beginning of the period, before the Germanic peoples had entered the Roman Empire in force. Hrothulf, the equivalent of Hrolf Kraki, and the contemporary kings of Sweden, come at the end. The fall of Hygelac, almost certainly recorded by several historians including Gregory of Tours as circa 520-530, and quite possibly the associated fall of the Geatish kingdom, come near the end. The more mythical 50-year reign of Beowulf (though he himself was not necessarily completely so) is fitted in to a fictional time slot after that.
Now these stories could not have been encapsulated in song until after the events, obviously; so as a body of legend and heroic song they date at earliest from the early sixth century or perhaps the mid sixth century. They may have been brought to Britain at any time between then and the composition of Beowulf itself, which may have been any time between 700 and 1000. But many of the same stories are reflected in the catalogue-like poem Widsith, which we have no reason to believe has any direct textual connection with Beowulf. It seems more than coincidental that two of the stories given extended mention in Widsith are the prowess of Offa of Angle and the Hrothgar-Hrothulf-Ingeld debacle. We know that the Ingeld story was popular in England from Aldhelm’s Quid Hinieldus cum Christo? And this story, like the downfall of Hygelac, belongs near the end of the chronological period covered by the heroic legends.
So it seems that there was probably a package of stories, culminating in the Dane/Heathobard conflict, forming a native tradition. The ‘warrior’ society which passed the legends down were the people who brought them to Britain. But as the stories could only have come together in the early sixth century they are most likely to have been brought here in or after the early sixth century, rather than by anyone who settled here before about 525.
Chambers’s views support this: ‘We must conclude then that all this Scandinavian tradition probably spread to the Angles whilst they were still in their old continental home, was brought across to England by the settlers in the sixth century, was handed on by English bards from generation to generation, till the poem of Beowulf as we know it was formed in England’ (Chambers 1963:101) [R. W. Chambers, Beowulf, 3rd edn. with Supplement by C. L. Wrenn, Cambridge, 1963, Part I, Chapter iii, p. 101]. And again, ‘It is noteworthy that, whereas there is full knowledge shown in our poem of those events which took place in Scandinavian lands during the whole period from about 450 to 530—the period during which hordes of Angles, Saxons and Jutes were landing in Britain—there is no reference, not even by way of casual allusion, to any continental events which we can date with certainty as subsequent to the arrival of the latest settlers from the continent. Surely this is strong evidence that these tales were brought over by some of the last of the invaders, not carried to England by some casual traveller a century or two later.’ (Chambers 1963: 104) [R. W. Chambers, Beowulf, 3rd edn. with Supplement by C. L. Wrenn, Cambridge, 1963, Part I, Chapter iii, p. 104].
It is notable that the heroic legends of the English people do not concern England. They are all based on the Continent. In other words, the Anglo-Saxons’ heroic age took place on the Continent. Moreover, the centre of that heroic age seems to have been southern Scandinavia, not Germania. Of course they clearly knew about the peoples who settled in Gaul, but the centre of gravity seems to be further north. The oldest legend which seems to be about themselves is the story of the first Offa, centring on the River Eider in Schleswig-Holstein.
The evidence of early settlement is found in existence before 500 in all the areas that were later to become the nucleus or a part of future kingdoms, apart perhaps from (Deira and) Bernicia, but the people who formed these settlements were not the purveyors of heroic legend. Most of the events were only then happening and had not yet been elevated to the status of poetic legend. These settlers were not organized as kingdoms or proto-kingdoms and there is no real reason to think of them as independently organized at all, except perhaps in very local groups in Kent, Sussex, and perhaps the upper Thames valley. They were just settlers. They may have been settled among or in close proximity to British inhabitants, as seems possible at Dorchester from the archaeology, and in places like Deira and Lindsey, judging from the persistence of the British district name.