Aberthaw derives its name from the Welsh word 'aber', meaning estuary or river mouth, of the river Thaw. The existence of a safe, natural harbour provided an early impetus for the area's development and trade. There were settlements in the 2nd and 3rd centuries, substantiated by Roman pottery, shells and tiles that were discovered when a new pipeline was laid through East Aberthaw in the 1950s. Excavations in Well Road revealed the foundations of walls which may have belonged to the Roman settlement, while further discoveries of coins, jewellery, tiles and Samian ware pottery suggested that the nearby bay served as a landing point or port during the Roman invasion. The Shrunken Village at West Aberthaw, considered an Ancient Monument in Glamorgan, consisted of a shrunken hamlet within a narrow strip of St. Athan parish which extended to the Bristol Channel.