The Welsh manor (maenor) of Castle Morris lay within the ancient Cantref of Pebediog (later the Hundred of Dewisland).

[1] The manor was granted to Maurice FitzGerald, Lord of Lanstephan by his brother David FitzGerald, then the second Norman approved bishop of St David's,[2] Castle Morris may have acquired its name (Castell Maurice) in the 12th century from Maurice FitzGerald, but it may be a far more ancient relic of the pre-Norman Welsh name - Castell Marlais - Marlais then being the name of the reach of the Western Cleddau river which flows immediately below the village.

[3] To the northeast of the village crossroads is the Grade II-listed farmhouse of Pencnwc, a substantial early and late 19th century building that was formerly part of the Bishop of St Davids' estate, leased by Abraham Leach in 1843, and occupied by William Evans.

[4] The farm occupies the site of a former timber castle with stone foundations, of which there are no longer any visible remains.

[6] In 1910 the village shop, smithy, cottages and 43 acres of land were put up for auction, but bidding only reached £1,900 and the lot was withdrawn.