"A parish in the Union of Corwen, partly in the hundred of Edeyrnion, county of Merioneth, and partly in that of Isaled, county of Denbigh, 10 miles (NW by W) from Corwen; containing 428 inhabitants. ..... The village, consisting of only four houses, is situated on the small river Alwen, a rapid stream issuing from Llyn Alwen, in the mountains, about five miles north-west of the village, and forming, for the greater part of its course, the north-eastern boundary of the parish. ..... There are some excellent meadows on the banks of the Alwen, affording pasturage to some herds of black cattle peculiar to this part of the principality, which are kept chiefly for the dairy; and the mountain lands, covered with fine heath, are depastured by numerous flocks of sheep of the small Welsh breed."
[ A Topographical Dictionary of Wales, 1833 & 1849, Samuel Lewis]
The parish comprises the township of Cefn Post (in Merionethshire); and the townships of Maes yr Odyn, Llysan, and Cysilog (or Llysyllog) in Denbighshire.