When the discovery of a new Iron Age hoard was announced this week, a video was released showing a long table laid out with ancient metalwork. The last time I saw anything similar was when the media were shown the Staffordshire Hoard in 2009. That was a pile of Anglo-Saxon military gold and silver, bought by museums in the West Midlands for well over £3 million. Its discovery launched a decade of research by teams of archaeologists and historians. Its impact on thinking about seventh-century England will continue for generations.

The Melsonby hoards – two collections of broken iron and bronze (or other copper alloys) buried in adjacent ditches in the first century AD – could be just as thrilling. Already there are features of the hoards that have never been seen before in Britain.

For now, there are two key questions. What has been found? And what can we guess it might mean? The latter is informed by the site’s Yorkshire location – though not, as has been reported, because it shows that the north of England can give as good as the south.

The hoards were found by detectorist Peter Heads just before Christmas 2021, and excavated by Durham University archaeologists the following summer. Tom Moore, the head of Durham’s archaeology department, expected a week in the field. It took them two months. It’s still early days, but after two years’ conserving and cleaning we can begin to describe the deposits.

The larger group includes 28 iron tyres, probably from four-wheeled carts. While these type of carts have been found in rich Iron Age graves on the European continent, before now they have not been seen in Britain. Some of the Melsonby tyres are more than a metre in diameter – too hefty to be from two-wheeled chariots.

With these are at least 14 sets of bronze horse-harness fittings with great dollops of glass and Mediterranean coral, three spearheads and parts of a shield, and two unusually large sheet-metal cauldrons. One of these features is what may be a unique fish design, described to me by Sophia Adams at the British Museum as ‘a sardine with a La Tène tail’ – Roman flesh with a Celtic motor. The other is an Etruscan-looking wine-mixing bowl, with attached cast human faces. And there is a mirror. Mirrors are typically found in female graves, but here there are no human remains, and the mirror is iron, and particularly large.

The other finds group is smaller, but more compact. So much so, that excavation outdoors was deemed too risky, and the whole thing was lifted in a block of soil and twisted metal; textile traces suggest the collection may have been wrapped in fabric. It’s still being cleaned in the British Museum, but the pieces are so intimately packed, with some of them fused by the heat of a fire, that the current feeling is they will be left as they had been buried, spearheads, harnesses, wheel parts and more crammed together in a silent echo of dramatic events two millennia ago.

So what was going on? Scientific dating by Historic England (which also helped fund the dig) is in progress, but in the meantime, stylistically the two collections look to come from the same period. They seem to have been buried shortly before Roman armies reached northern Britain. Remarkably, a third collection of horse gear, known as the Stanwick Hoard, was found nearby (its exact location was not recorded) in 1843. A bronze horse head from the site, thought to be from a decorative bucket, is on display in the British Museum. This hoard was named after an exceptional earthwork site a mile or so away, where dramatic banks and ditches, on occasion reinforced with stone walling, surround a large open space. Excavation and survey over the past century have led archaeologists to conclude that Stanwick was a place of tribal assembly at the junction of major Iron Age routes. Excavation a little to the south, during recent roadworks at Scotch Corner, revealed Iron Age and early Roman houses and workshops laid out beside roads. Finds from both locations include fine Roman items imported before the conquest. At Scotch Corner, Iron Age smiths were minting coins.

Such evidence, spectacularly reinforced by these new discoveries, is enough to tell us that there was something exceptional about the Stanwick-Scotch Corner area in the late first century BC and early first century AD – for any part of Britain. Tacitus, writing less than a century later, knew it too. The remains are at the heart of what was then the territory of a large tribe or confederation named the Brigantes. Tacitus describes an aristocratic soap opera of warring chiefs. Cartimandua – a contemporary of Boudica and the only other named queen from this time – handed a fleeing resistance leader, Caratacus, over to Rome, which came to her rescue when she was attacked by a former lover’s army, until the tribe itself was subjugated by Roman soldiers.

Back at the hoards, a notable feature is that everything was deliberately broken up. Tyres are buckled. A large stone punched a hole in the bottom of the upturned cauldron. Timber not already removed was burnt to charcoal. For the archaeologists, this is a recognisable display of wealth and power: whoever was responsible, could afford to lose such treasures – and wanted to be seen destroying them. Perhaps deceased royalty, not yet found, were buried nearby. Were bombastic chiefs wrecking their own inheritance? Or were victors destroying the legacies of the conquered? And who saw themself in the polished face of the great Melsonby iron mirror?

Selected pieces from the hoards can be seen in The Yorkshire Museum, which is appealing for £500,000 to save them from private sale and complete conservation