Evidence of Dark Age beach parties suggests Celts were connoisseurs of Byzantine wine

Dark-age Celts in Britain at the time of King Arthur were so keen on Mediterranean wine that they were prepared to swap their most valuable natural asset to satisfy their sophisticated palates.

Archaeological discoveries in south Devon suggest Celtic aristocrats were "buying" North African, Palestinian and other eastern Mediterranean wine by supplying the Byzantine empire with tin.

The discovery of the remains of 10 huge beach parties – thought to have been held to celebrate the arrival of Byzantine traders – indicates the existence of a complex commercial arrangement when the rest of the domestic economy was stagnating.

The find helps to link a West Country Celtic kingdom called Dumnonia – associated with King Arthur – with the successor to the Roman imperial era, the Byzantine empire. The finds may also lead to the discovery of a Celtic palace near by.

Historians had thought that, when the Romans left Britain in AD410, strong links with the empire were severed. But the scale of contact now being revealed suggests that close links were re-established with the empire's Byzantine successor about a century later.

Archaeologists excavating at the mouth of the river Avon in Devon have unearthed 530 fragments of 6th-century eastern Mediterranean wine amphorae, mainly from North Africa, Palestine and Turkey, and 2,400 pieces of animal bone – the detritus of the great parties. The evidence indicates that the hosts and guests sated themselves on beef, pork, mutton, venison, rabbit, duck and chicken – all washed down with generous quantities of Byzantine wine.

The archaeologists have also found four open-air camp fires and fragments of posh Byzantine tableware. It is probable that the Dumnonians were acquiring Mediterranean wine and Byzantine consumer durables in exchange for tin. A metal-working hearth has been found as have 20 fragments of metal slag. And the location is less then a mile from a probable Byzantine shipwreck site from which divers have recovered 43 ingots of Dumnonian tin. Evidence shows that the ingots were made on a sandy surface – potentially the same beach.

The discovery near Bantham, 14 miles south-east of Plymouth, has produced the second largest quantity of Byzantine-made Dark Age pottery found in Britain. The only site that has produced more is at Tintagel in Cornwall – where King Arthur is said to have been conceived.

Tintagel and Bantham were within the Dark Age British kingdom of Dumnonia which covered what is now Cornwall and Devon. Tintagel is known to have been of very high status and Byzantine trade was conducted exclusively with the west of Britain, when the east was occupied by barbarians from Germany – the Anglo-Saxons. The new discovery is, therefore, likely to trigger a search for Tintagel-style fortresses or palaces near by.

The exact nature of the relationship between the Byzantines and south-west Britain is a mystery. Was it a purely commercial relationship or did the kingdom of Dumnonia briefly become a semi-detached part of the Byzantine empire 100 years after the Romans had left?

Peter Weddell, the head of Exeter Archaeology, which is working on the Bantham site, said: "These very important finds are now being examined in detail and will no doubt shed crucial new light on Dark Age Britain and its relationship with the wider world."