Arwystli

Arwystli was a cantref in mid Wales in mediaeval times, located in the headland of the River Severn. It was chiefly associated with the Kingdom of Powys, but was heavily disputed between Powys, Gwynedd, and the Norman Marcher Lords for hundreds of years, and was the scene of many skirmishes between those groups. Like many other cantrefs and subdivisions, it was divided up by the Laws in Wales Acts in the 16th century.

During the Roman era Arwystli formed part of the territory of the Ordovices, the Celtic tribe that controlled much of northern Wales. It is unclear when it formed as a distinct unit, but the name itself derives from the personal name Arwystl, borne by a disciple of Dubricius. The first reference to Arwystli occurs in the 11th-century Domesday Book, where it appears as the "hundred of Arvester". At some point it was subdivided into the commotes of Arwystli Is Coed and Arwystli Uwch Coed (Arwystli Below the Wood and Arwystli Above the Wood). Important settlements included Talgarth, Llandinam, Llanidloes, and Caersws. There is some conjecture that Arwystli may have been associated with the region known as Rhwng Gwy a Hafren (English: Between Wye and Severn). Hubert Hall suggests that it was one of the cantrefs of the obscure region once known as Cynllibiwg, located "between Severn and Wye", mentioned in the Red Book of the Exchequer.

In earlier times Arwystli was evidently considered part of the Kingdom of Powys, but over time its local rulers established ties with Gwynedd. Significantly, the cantref became part of the Diocese of Bangor, which covered Gwynedd, rather than the Powys-centred Diocese of St Asaph. As such Arwystli was the scene of periodic bloody disputes between the two kingdoms. Though the cantref mostly consisted of inarable moorland, it did contain some valuable farmland in the river valleys and offered strategic access between Mid Wales and the Welsh Marches. In the late 11th century it was taken by the Norman leader Roger de Montgomerie, though his claim to it was disputed by Robert of Rhuddlan, who controlled most of North Wales at the time. It remained in the hands of Roger's heirs until the earlier 12th century, when it was retaken by Welsh lords. Over the next centuries Powys and Gwynedd resumed their violent struggle, and the Arwystli dynasty changed allegiances several times.

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