Builth

Buellt or Builth was a cantref in medieval Wales, located west of the River Wye. Unlike most cantrefs, it was not part of any of the major Welsh kingdoms for most of its history, but was instead ruled by an autonomous local dynasty. During the Norman era it was associated with Rhwng Gwy a Hafren, a region independent of the Welsh monarchies and controlled by Norman Marcher Lords. In the 16th century, it was reorganized as a hundred and joined with the former kingdom of Brycheiniog to form the county of Brecknockshire.

The name Buellt, also rendered Buallt, comes from the Welsh words bu, meaning "ox", and gellt (later gwellt), meaning pasture. This was later anglicized to Builth, as in the modern town of Builth Wells.

Situated in the valley of Afon Irfon, Buellt's boundaries were roughly the Cambrian Mountains to the north, the River Wye to the east, the Mynydd Epynt range to the south, and Ceredigion to the west. It was closely associated with the territories of Gwrtheyrnion, Elfael, and Maelienydd, and as such was often considered part of the region known as Rhwng Gwy a Hafren (English: Between Wye and Severn) despite being west of the Wye. The cantref was divided into four major commotes, whose boundaries are unclear: Treflys, Pebuellt, Dinan, and Is Irfon. Most of Buellt's major sites were located along the Irfon, including the courts of the commotes and the major church at Llanafan Fawr, dedicated to Saint Afan Buellt, the cantref's chief saint.

...
Wikipedia