Fanad encompasses the parishes of Clondavaddog, Killygarvan and parts of Tullyfern and Aughinish. It measures approximately 25 km north-south measured from Fanad Head to the town of Ramelton and approximately 12 km east-west measured between the townlands of Doaghbeg and Glinsk. The southern boundary of Fanad has been the subject of some dispute over the centuries. In the 16th century, during the time of the MacSuibhnes as rulers of Fanad, it was stated that the territory of Fanaid stretched as far south as the River Lennon between Kilmacrennan and Ramelton. In 1835, the surveyor John O’Donovan referred to Rathmullan as the capital of Fanad, and he also refers to Clondavaddog as “the most northern parish of Fanaid”, suggesting that Fanad included parishes other than Clondavaddog.O’Donovan also noted that “The inhabitants of Inishowen state that Fanaid extends from Rathmeltan to Mulroy Lough, but the natives of the Parishes of Killygarvan, Tully and Aughnish, who considered themselves civilised, deny that they themselves are of the men of Fanaid”.