pennies, previously-unknown "two emperor" coins showing the heads of both Alfred and Ceowulf and dating to around 879. The find hints at an alliance between the kingdoms of Wessex and Mercia. Gareth Williams, curator of early medieval coins at the British Museum, commented in 2019 "These coins enable us to re-interpret our history at a key moment in the creation of England as a single kingdom". The treasure was found by two metal detectors operating outside the law, and they were convicted. A ravaging of Archenfield by the Danes in 905 is reported in the 1870-72 Imperial Gazetteer of England and Wales: In 915 the area faced an incursion from Vikings led by Ohter and Hroald, coming from the River Severn. After first capturing Cyfeiliog (Cimeliauc), the Bishop of Llandaff, they were defeated in battle by the combined forces of Gloucester and Hereford, possibly at "Kill Dane Field" near Weston-under-Penyard. According to one of the Anglo-Saxon Chronicles, Cyfeiliog, referred to as Cameleac in the Worcester Chronicle, was bishop in Archenfield, and King Edward the Elder ransomed him for £40, but in the view of Michael Swanton the evidence for a bishopric there is weak, and the text can be read that he was taken in Archenfield. Thomas Charles-Edwards refers to "Bishop Cyfeilliog, who was probably bishop of Ergyng, or at least captured in Ergyng". He sees the payment of a ransom by the West Saxon king as evidence that the far south-east of Wales then lay in the sphere of power of Wessex rather than Mercia. The Worcester Chronicle for 915 states that the "jarl Hroald and the other jarl Ohtor's brother" were killed and the raiders left the area, leaving some hostages as a peace bond. In the early 10th century, a document known as The Ordinance Concerning the Dunsaete records procedures for dealing with disputes between the English and the Welsh of Archenfield, who were known to the English as the Dunsaete or "hill people". It stated that the English should only cross into the Welsh side, and vice versa, in the presence of an appointed man who had the responsibility of making sure that the foreigner was safely escorted back to the crossing point. Archenfield, which lay outside the English hundred system, became a semi-autonomous Welsh district, or commote (Welsh cwmwd), with its own customs. Its administrative centre was at Kilpeck Castle. Its customs were described in