Marcher lordship in southeastern Wales; the castle and town of Brecon (Aberhonddu) stand at the confluence of the River Honddu with the Usk, northwest of Abergavenny, south of Builth Wells, and north of Merthyr Tydvil.
Norman knights, principal among them Bernard of Neufmarché, probed into the Welsh Kingdom of Brycheiniog in the late 11th century. In 1093 the King of Deheubarth, the overlord of Brycheiniog, was defeated and killed near the confluence of the Usk and the Honddu, where Bernard built the castle of Brecknock or Brecon. The lordship was extensive, controlling the upper valley of the Usk and the route between the Brecon Beacons and the Black Mountains; in the later 12th century it divided, its eastern sector becoming the lordship of Blaenllyfni.
Held at first by Bernard, then his son-in-law, Miles, Earl of Hereford,and Miles’s sons after him, the lordship came in 1165 into the hands of the Braose, one of the great Marcher families. In 1241 it became the property of the Bohuns, Earls of Hereford, extinct in 1373. One of their heiresses brought Brecon to the future King Henry IV on her marriage in 1380. In 1421 it was transferred to the Earl of Stafford, the representative of the other Bohun heiress, and stayed with that family, subsequently Dukes of Buckingham, except for a time after the execution of Duke Henry in 1483. After the execution of Edward, the last Duke, for treason in 1521, the lordship fell to the Crown.
In 1536 the lordship became part of the new Welsh county of Breconshire.