The mediaeval Welsh cantref of Arfon in north-west Wales was the core of the Kingdom of Gwynedd. Later it was included in the new county of Caernarfonshire, together with Llŷn and Arllechwedd under the terms of the Statute of Rhuddlan in 1284. The island of Anglesey faced it across the Menai Strait; to the east was the cantref of Arllechwedd, to the south the cantref of Eifionydd (which, together with Ardudwy, was part of the earlier kingdom of Dunoding), and to the west was the cantref of Llŷn.