Although, following the Treaty of Perth, Suðreyjar's successor state, the Lordship of the Isles, fell under the nominal authority of the Scottish king, it was not until 1475 that it was merged with Scotland (the occasion being the punishment of its ruler for an anti-Scottish conspiracy). The sheriffdom of Argyll was expanded to include the adjacent mainland areas from the Lordship. Following local government reforms in the 19th century, the traditional provinces were formally abolished, in favour of counties aligned with sheriffdoms, so Cowal became merely a part of the county of Argyll.