Penboyr (Welsh: Penboyr) is a hamlet (place) in the county of Carmarthenshire in west Wales consisting of a number of houses, smallholdings, farms and a church."This is a small area within modern Carmarthenshire consisting of regular rectangular fields and dispersed farms. It lies within the medieval Cantref Emlyn, in Emlyn Uwch-Cych commote. Cantref Emlyn had been partly brought under Anglo-Norman control in c.1100 when Emlyn Is-Cych commote to the west was reconstituted as the Lordship of Cilgerran. Numerous castles were established in Uwch-Cych comote - none of which has any recorded history - but the commote was back under Welsh control by the 1130s, where it remained throughout the 12th and early 13th centuries.