For over five centuries this area, the feudal barony of Arrochar, was held by the chiefs of Clan MacFarlane and before them by their ancestors the barons of Arrochar. The family is Celtic in the male line and native to their Highland homeland of tall peaks and deep lochs just above the waist of Scotland. The settlement was a key target for Viking raiders who took their boats 2 miles overland to Tarbet to attack the unprotected inland settlements at Loch Lomond before their defeat in 1263 at the battle of Largs.
The western end of Arrochar marks the traditional boundary of Argyllshire and Dunbartonshire, and this remained the case under local government reorganisation in 1975. However in 1996 the boundaries of Argyll and Bute and West Dunbartonshire were substantially redrawn, bringing the whole area into Argyll and Bute.