1. Dyffryn Amanw

      An English valley (presumably next to the mountain Mynydd Amanw) where Arthur’s warriors fought one of their many battles against Twrch Trwyth and his piglets.

      Two of the piglets - Banw and Benwig - were killed before Twrch Trwyth fled on to Llwch Ewin.

    2. Dyffryn Llwchwr

      A valley in England where Arthur’s warriors fought two of Twrch Trwyth’s piglets - Grugyn Silver Bristle and Llwydawg the Killer. The piglets escaped after killing many warriors.

The word dyffryn is popularly derived from dwfr, which is the Welsh word for water, and hynt, which means a way, a course. That is a water-course, or a vale, through which a river takes its course. It may be a compound of dwfr-bryn, signifying a hilly place through which water flows. See also notes under Glyn.