It was divided into the commotes of Ystumanner (administered from Castell y Bere at Llanfihangel-y-Pennant) and Talybont (possibly centred on Llanegryn where there is a mound).

[2] The cantref was effectively abolished in 1284 following the Statute of Rhuddlan with the area being reorganised with the addition of some neighbouring cantrefi to form the county of Merionethshire.

The county of Gwynedd was divided into five districts, one of which was called Meirionnydd, reverting to the Welsh spelling of the name Merioneth.

The Meirionnydd area merged with the neighbouring Arfon and Dwyfor districts to become a county, which the government originally named Caernarfonshire and Merionethshire.

[6] During the transition to the new system, the shadow authority requested a change of name from Caernarfonshire and Merionethshire to Gwynedd.