Истрад-Тиви
The area that would become Swansea is located on the eastern edge of the cwmwd of Gwyr, in the Cantref Eginawc, the easternmost Cantref of Ystrad Tywi. The area was noted for its valuable land and was highly contested by the early Welsh kingdoms. During the Viking Age, the mouth of the Tawe became a focus for trade, and a trade post may have been founded sometime between the 9th and 11th centuries. When the Normans took control of the settlement, they built Swansea Castle and minted coins bearing the names "Swensi", "Sweni" and "Svenshi" .