"A hamlet, in the parish of Llanrhaiadr in Kinmerch, Union of Ruthin, hundred of Isaled, county of Denbigh; 3 miles (SSW) from Denbigh, containing 176 inhabitants. ..... A river rises in the hilly part of the hamlet, from two sources, after the union of the waters from which it sinks underground, and does not appear again, until it bursts forth in a copious stream from a limestone rock at the well of St. Dynog, near the parochial church.
[ A Topographical Dictionary of Wales, 1833 & 1849, Samuel Lewis]
The ecclesiastical parish of Prion was created, by an order in Council, on 23 January 1860, and extended by an Order in Council on 22 February 1879, out of the ancient parish of Llanrhaeadr yng Nghinmeirch. It comprises the townships of Llanrhaeadr yng Nghinmeirch, Prion and Trefydd Bychain; and portions of the townships of Llewesog, Segroit Ucha, Segroit Isa, and Cader.