UKC

Calling all those Welsh scholars, or anyone with some more knowledge than me. Help me understand this. The Welsh for Brecon Beacons is  Bannau Brycheiniog but the Welsh for Brecon is Aberhonddu (mouth of the Honddu I believe) and the Welsh for Beacons is Goleuadau! Where does Bannau Brycheiniog come from. I'm guessing Brycheiniog must relate to Brecon because we have the Theatr Brycheiniog. I did ask a Welsh person in Brecon and they said 'It's just what it's called isn't it.' Which was not massively helpful.

Brychan was a 5th C Welsh king, Brecon would have been at the heart of his rather small kingdom. When the Normans arrived they obviously realised it was a good spot for a castle, and presumably the county and town names got confused.

Bannau is the plural of ban, meaning peak, mutated to Fan in Pen Y Fan.

Not sure, but ban (plural - bannau) is a Welsh name for a peak or summit, and the Welsh name for Brecknockshire/Breconshire is Brycheiniog, or Sir Frycheiniog. The Peaks of Brecknockshire. Aberhonddu is where the Afon Honddu meets Afon Wysg (River Usk).