Archenfield (Old English: Ircingafeld) is the historic English name for an area of southern and western Herefordshire in England. Since the Anglo-Saxons took over the region in the 8th century, it has stretched between the River Monnow and River Wye, but it derives from the once much larger Welsh kingdom of Ergyng.
The name Archenfield is derived from the older and larger Welsh kingdom of Ergyng (or Ercic), which in turn is believed to derive from the Roman town of Ariconium at Weston under Penyard. After the withdrawal of the Roman legions from Britain in 410 AD, new smaller political entities took the place of the centralised structure. King Peibio and his descendants are rulers of the area attested from about 555 AD until, in the middle of the 7th century, Onbraust of Ergyng married Meurig of Gwent and the two neighbouring kingdoms were combined. Saint Dubricius (known in Welsh as Dyfrig), a prince and bishop, was important in the sub-Roman establishment of the Christian church in the area. Ergyng eventually became a mere cantref, the Welsh equivalent of a hundred.
By the 8th century, the expanding power of Mercia led to conflict with the Welsh and by the beginning of the 9th century the western Mercians, who became known as the sub-kingdom of Magonset, had gained control over the area and nearby Hereford. During the rest of the century they moved its frontier southward to the banks of the Dore, the Worm Brook and a stream then known as the Taratur, annexing northern Ergyng. The sites of old British churches fell to Mercia, and the Britons became regarded as foreigners – or, in the Old English language, "Welsh" – in what had been their own land. The rump of Ergyng then became known to the English as Arcenefelde or Archenfield. There is no evidence that Offa built his famous Dyke across the area, probably because it had already been assimilated into Mercia by the late 8th century.