In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Bryn Gwyn like this:
BRONGWYN, or Bryngwyn, a parish in the district and county of Cardigan; near the river Teifi, 2 miles NW of Newcastle-Emlyn r. station. It has a post office under Carmarthen. Acres, 1,620. Real property, £1,317. Pop., 339. Houses, 80. The property is divided among a few. The living is a vicarage, annexed to the vicarage of Penbryn, in the diocese of St. David's. The church is good; and there is an Independent chapel.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Bryn Gwyn has changed, please see our redistricted information for the modern district of Ceredigion. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Bryn Gwyn and units named after it.
GB Historical GIS / University of Portsmouth, History of Bryn Gwyn, in Ceredigion and Cardiganshire | Map and description, A Vision of Britain through Time.
Date accessed: 30th July 2015
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Bryn Gwyn".