The history of the diocese of St Davids is traditionally traced to that saint (Dewi) in the latter half of the 6th century.

Records of the history of the diocese before Norman times are very fragmentary, however, consisting of a few chance references in old chronicles, such as Annales Cambriae and Brut y Tywysogion (Rolls Series).

The sixth century bishop St Ismael is honoured on 16 June.

[9] The geographic remit consisted of the City and County of Swansea, Neath and Port Talbot, and the traditional counties of Brecknockshire, Cardiganshire, Carmarthenshire, Pembrokeshire and Radnorshire - an area of 9,310 square kilometres (3,590 sq mi) roughly.

There were a total of five deaneries in the Diocese of Menevia, all of which cover several churches in that area, overseen by a dean.