The Afon Brân is a tributary of the River Towy in mid Wales. Its headwaters rise in Irfon Forest in the northeastern corner of Carmarthenshire as the Cynnant Fawr and Afon Lwynor and the river assumes the name of Afon Brân at their confluence to the north of the village of Cynghordy. Its major tributary is the Afon Gwydderig which joins it at Llandovery. Other tributaries include the Nant Bargod, Cynnant Fach, Afon Gwyddon, Nant Hirgwm, Nant Cwm-neuadd, Bawddwr and Afon Crychan with its own minor tributary the Afon Dulais.