The sudden appearance of new coin designs hints that some tribes in south-eastern Britain might have been under the control of a Belgic elite and adopted aspects of their culture as early as 100 - 80 BC.

The distribution of Aylesford-Swarling pottery in south-eastern Britain has also been associated with the Belgae; however, recent studies proposed that migration might not have played as significant a role as once thought, with increased trade connections being more important, although this remains uncertain.

[10][11][12] The Regni entered a period of historical documentation around 75 BC, with the emergence of written records and the rise of a literate society, accompanied by a more complex economic system.

Various groups' movements were no longer tracked solely through pottery artefacts but also through the identification of coins, marking a level of literacy, the aggregation of core cultures in specific regions, and the introduction of monetary transactions for trading surplus goods.

The Gallo-Belgic tribes, also known as Celts, integrated their dominance into the existing social structure rather than replacing it; even during the later Roman era, indigenous Neolithic inhabitants coexisted with Iron Age urban residents in Sussex.

Significant newcomers like Commius of the Atrebates, who sought sanctuary in Britain around 52 BC, brought and promoted a level of civilisation influenced by Rome.

The Atrebates settled across a wide area encompassing Hampshire, Wiltshire, and parts of eastern Sussex, with some falling under the rule of the Catuvellauni by 25 BC.

The influence of the Atrebates extended toward the Ouse and partially into the Weald, while tribes in the northeast and Kent maintained a more defensive stance, with Mount Caburn being a strongly fortified boundary town.

The new ruling class notably abandoned the large developed hill-forts at the Trundle and Cissbury in favour of sophisticated urban centres on the coastal plain.

It's believed that the Cymenshore/Mixon rocks were submerged around the 7th or 8th century AD, Large iron age shrine/votive site, also of significance is the Romano-Belgic Palace found at Fishbourne, which included a coin mint and shrine at Ratham, alongside ironworks at Boxgrove.

Various settlement enclosures at Warningcamp may be linked to the Rewell Wood tribes, while the Burpham vicinity yielded Iron Age artefacts along with bone fragments from burials and signs of earthworks.

Wittering, which is now submerged, served as another trade centre at Chichester Harbour inlet, while Tournerbury hill fort is positioned approximately 100 metres from the Solent shoreline on nearby Hayling Island, just over the modern border with Hampshire, where Iron Age and Roman pottery have been discovered.

Funtington features Coldharbour trade activities along the River Lavant, along with earthworks, cross dykes, a camp, and a field system, while a small quantity of gold and silver Celtic coins was discovered.

Textile production preceded leatherwork as the primary industry, supported by the presence of salt producers along the Selsey coast, indicating a thriving trading economy that raised the standard of living for the ruling elite.

[15] Descriptions by Tacitus portray the south-eastern Britons as having similarities with their Gaulish counterparts: valiant yet hesitant in battle, fond of adorning themselves with woad, and possibly open to polyandry, though the accuracy of this claim is ambiguous.

The inland areas of Britain were inhabited by people claiming native heritage, while coastal regions were populated by migrants from Belgium who arrived to engage in warfare.

[16][17] This central area likely served as the heart of the Belgic-influenced Regni tribe, stretching from the boundaries of Hampshire to the Trisantona Fluvius (the River Arun), meeting the English Channel at Littlehampton.

[18][19] Situated geographically along the southern coast of Britain, they likely assimilated more advanced practices and traded with Continental tribes until the Roman conquest of Gaul.

The Regni, in conjunction with the Atrebates, seemingly saw Rome as a chance to enhance their commerce in opulent textiles, hunting dogs, and Iron goods, thus encouraging a reciprocal exchange of concepts that enriched their culture and technology, potentially giving them an advantage over less developed neighbouring tribes.

Some have assumed that Cogidubnus must also have ruled over the civitates of the Belgae and the Atrebates, while Miles Russell has suggested that the kingdom could have extended northwards to the south and east Midlands, and westwards to Bath.

After Cogidubnus's death, the kingdom would have been incorporated into the directly ruled Roman province and divided into its constituent civitates, such as the Regni, Atrebates and Belgae.

Likewise, the theory that Cogidubnus was created legatus, a rank only ever given to senators, is based on reconstructing the damaged Chichester inscription to read as Cogidubni regis legati Augusti in Britannia ('king and imperial legate in Britain').

The Commios Ladder head silver units (30 - 45 BC) depict a Celtic fertility Goddess with unique features like a lentoid eye, swollen cheeks, and a bulbous chin.

Dating back to 55-45 BC, the Sussex Lyre silver unit features a portrayal of a Diademed goddess head with a distinctive pointed nose, wearing a neck torc and curly hair, possibly representing Trisantona, linked to the River Arun.

The Aedui, Sequani, and Lingones underwent political transformations early in the 1st century BC, implementing oligarchic structures similar to those of the Roman administration.

Like the Gauls, the creators of British coin images made a clear distinction between abstract state symbols and depictions of powerful protective goddesses.

The depiction of the Roma goddess by the Regini and Iceni resembles a cult image, possibly representing a British equivalent to deities like Diana/Artemis or Minerva/Pallas Athene.

Coin design often coincided with political transformations and administrative reforms, and the adoption of Roman imagery suggests the emergence of tribal leagues, larger kingdoms, and oligarchic states.

The word for a People or tribal state in Gaul and Britain at that time, Teuta or Touta, was a feminine noun, similar to the Latin Civitas, allowing for personification as a female deity.

At Wiggonholt, on a tributary of the River Arun, a large lead tank with repeated chi-rho motifs was discovered in 1943, the only Roman period artefact in Sussex found with a definite Christian association.