Истрад-Тиви
Ystrad Tywi was transformed into the county of Carmarthen when Edward I enacted the Statute of Rhuddlan in 1284 following the success of his war against Llywelyn ap Gruffudd, Prince of Wales. Though Gŵyr had by now become part of Glamorgan, the rest of Eginawc was later restored to Ystrad Tywi, which was joined with Gwarthaf (except Efelfre) to form the modern county of Carmarthenshire.