According to tradition Iestynap-Gwrgan, the last prince of Glamorgan, had a residence somewhere near the present town, but Fitzhamon, on his conquest of Glamorgan, gave the district between the Neath and the Tawe to Richard de Granaville (ancestor of the Granvilles, marquesses of Bath), who built on the west banks of the Neath first a castle and then in 112 9 a Cistercian abbey, to whose monks he later gave all his possessions in the district.
The southern edge of the county is formed by the scarps and moorlands of the Carboniferous Limestone and Millstone Grit (both of which form also the outlier of Pen-ceryg-calch north of Crickhowell), while the lowest beds of the Coal Measures of the South Wales coalfield are reached in the Tawe and Neath valleys (where the beds are much folded) and near Tredegar and Brynmawr.
The see of Llandaff comprises Monmouthshire, all Glamorganshire as far west as the Tawe, and some parishes in Brecon and Hereford.
The name Swansea stands for Sweyn's "ey" or inlet, and may have been derived from King Sweyn Forkbeard, who certainly visited the Bristol Channel and may have established a small settlement at the estuary of the Tawe.
The Taff, the Nedd (with its tributaries the Hepste and the Mellte) and the Tawe, all rise on the south of the Beacon range, and passing through Glamorganshire, flow into the Bristol Channel, the upper reaches of the Nedd and its tributaries in the Vale of Neath being deservedly famous for its scenery.