DEHEUBARTH came into existence in 920 when Hywel Dda combined the kingdoms of Dyfed and Seisyllwg. It covered the areas now known as Ceredigion, Carmarthenshire and Pembrokeshire, but also took in Gower. Hywel had his base at Dinefwr, near Llandeilo, but the area was later repeatedly overrun by the Welsh of the north and east, including Llywelyn ap Seisyll of Gwynedd and Rhydderch ab Iestyn of Morgannwg. There were then repeated Norman incursions but in the 12th century Lord Rhys briefly got the kingdom back to the status Hywel had reached around 200 years earlier. But when he died, his kingdom was divided among his several sons and after Edward I’s conquest, it was divided into Ceredgion, Carmarthenshire and Pembrokeshire.