During the Second World War, workers digging peat for the construction of the RAF Valley airfield on Anglesey/Ynys Mon came across a hoard of over 150 Iron Age objects, including weapons, jewellery and tools. The find offers us a glimpse into the trade networks and craftsmanship of ancient Welsh society. The superb collection includes seven swords, six spearheads, fragments of a shield, part of a bronze trumpet, two gang chains, fragments of iron wagon tyres and horse gear. In addition, blacksmith's tools, fragments of two cauldrons, iron bars for trading and animal bones were found.

The Cors yr Ynys bog is at the southern margin of Llyn Cerrig Bach, a small lake in the north-west of the island. The location is said to be an important centre for the Ancient Celtic Druids. Some of the offerings may have been made in response to the threat from the Romans.