"A parish in the Union and hundred of Ruthin, county of Denbigh, 2 miles (S) from Ruthin, on the road to Wrexham and Llangollen; containing 1254 inhabitants. This parish is situated on the banks of the river Clwyd, at the upper extremity of the spacious vale to which that stream gives its name; and abounds with interesting and beautifully varied scenery. ..... The substratum of the parish is limestone, of which great quantities are procured for building, and also for burning into lime: the quarries and limekilns afford employment to a considerable portion of the population."
[A Topographical Dictionary of Wales, 1833 & 1849, Samuel Lewis]
The ancient parish of Llanfair Dyffryn Clwyd comprised the townships of Eyarth, Garthgynan, Derwen-Llanerch, and Faenol.