From The Powys Montgomeryshire Village Book: "The parish takes its name from the brook which flows into the river Severn below the church. "Aber" meaning mouth of the river; "haf" meaning summer, and "hesb" meaning dried up or barren, becomes Aberhafesp - the mouth of the summer-dry brook.

St. Gwynog's church lies in the southeast of the parish. There has been a church here since the 12th century, and a large yew tree west of the tower has been estimated at over 800 years old."