Arwystli

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". 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. 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 (). 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. ==High Middle Ages==

In earlier times Arwystli was evidently considered part of the Kingdom of Powys, but over time its local rulers established ties with Gwynedd. It remained in the hands of Roger's heirs until the earlier 12th century, when it was retaken by Welsh lords. Gruffydd protested, and in 1277 Llywelyn plead his case to Edward, his suzerain, hoping for a quick resolution. The 1277 Treaty of Aberconwy guaranteed that Edward would provide full consideration to Llywelyn under the law, and also that disputes be settled "according to the laws of Wales for cases arising in Wales". Llywelyn claimed that Arwystli was part of Wales, and as such the dispute must be settled by Welsh law, rather than the English common law of the Marches. After the conquest the following year, Edward upheld Gruffydd's claim, solidifying Powys' claim over Arwystli. It was part of the historic county of Montgomeryshire until 1974, when the area became part of the new county of Powys. ==Notes==