Tarbertshire, or the sheriffdom of Tarbert, was a shire of Scotland until 1633, when it was annexed to Argyllshire. It comprised the mainland peninsula formed by Knapdale and Kintyre, together with the southern Inner Hebrides to the west. It has been suggested that Robert the Bruce, who extended Tarbert Castle, created or intended a sheriffdom there; however, the first reference to Tarbertshire is in 1481, when Knapdale was transferred to it from Perthshire. The shire town was Tarbert, but the sheriff court was latterly at Inveraray in Argyllshire. The Earl of Argyll family of Campbells often supplied the Sheriff of Tarbert and other officials of both Argyll and Tarbert.