County of Powys, Wales Genealogy
The county takes its name from the ancient Welsh Kingdom of Powys, which occupied the northern two thirds of the county's area, as well as lands now in Shropshire, England. The Kingdom of Powys came to an end when it was occupied by Llywelyn ap Gruffydd of Gwynedd during the 1260s.
The county of Powys was originally created on 1 April 1974, under the Local Government Act 1972, replacing Montgomeryshire; Radnorshire and Breconshire, the former administrative counties. These former counties were re-designated as administrative districts.
On 1 April 1996, the districts were abolished, and Powys was reconstituted as a unitary authority, with a minor border adjustment in the north-east (specifically the addition of the communities of Llansilin and Llangedwyn from the Glyndŵr district in Clwyd, along with the movement of the county border so that all of, and not as previously half of, Llanrhaeadr ym Mochnant was in Powys, all historically part of Denbighshire).
Powys is the largest county, in area, in modern Wales.