This is quite a rare Scottish surname. It is locational from the barony of Airth, near Stirling. Although it may be rare it is also ancient being first recorded in the year 1200 a.d. when William de Arthe was a charter witness of a land grant to the abbey of Cambuslang, whilst Richard Derth or more properly Richard d'Erth, is given as being a falconer to the king in 1212. It would seem that the barony of Airth was famous as a falconry centre, and it may be that the surname is rare because most if not all nameholders are descended from the original lord of the manor William de Arthe. It is also probable that the place name and hence the surname, is Norman-French in origin. If so it may be locational from a village in Northern France called Arte, although this is not proven. Rare or not the name was prominent in the history of Scotland during the Middle Ages. Sir Hugh de Erthe recorded as being bailiff to Sir John Cumyns in 1291, was probably the same knight who was captured by the English in 1296, and locked up in Dunbar Castle.