Brecknockshire
historic county, south-central Wales, named for Brychan, a 5th-century prince later known as Brycheiniog. Brecknockshire is mostly part of the present Powys county, although small areas in the south lie within the present Monmouthshire county and the county boroughs of Blaenau Gwent, Merthyr Tydfil, and Rhondda Cynon Taff.
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