St Clears Priory was a Cluniac cell of St Martin des Champs, founded between 1147 and 1184. The priory, dedicated to Mary Magdalene, was one of only two in Wales (the other being at Malpas, Monmouthshire). By the fourteenth century St Clydwen's Church, Llanglydwen (NPRN 308711) was a posession of the priory. St Cynin's Church, Llangynin (NPRN 309914) was formerly a chapelry belonging to the priory. Only the Prior and one monk were counted in 1350 and 1379, and the priory was disolved as an alien cell in about 1414.

The priory church is represented by the present parish church (NPRN103852) which includes twelfth and thirteenth century fabric.Buried features observed in the field immediately to the south (known as 'Parc Priordy' in 1912) are thought to represent the conventual buildings. The site of these buildings is designated a Scheduled Ancient Monument.

Sources include:
Cambria Archaeology, 2000, Carmarthenshire Churches, gazetteer, 48

RCAHMW, 6 December 2012