Cilymaenllwyd is a rural area, in north-west Carmarthenshire, which includes the villages of: Glandy Cross; Efailwen; part of Hebron; part of Login; Cwmiles and Pantycaws.
The community of Cilymaenllwyd borders the communities of Llanboidy and Henllanfallteg in Carmarthenshire, and Clunderwen, Mynachlogddu and Crymych in Pembrokeshire. The River Tâf forms the eastern boundary. The area is part of the foothills of the Preseli Mountains which rise to a height of 248 meters and is divided by the deep valleys of the River Taf and its tributaries.
The population of Cilymaenllwyd in the 2021 Census was 790 compared to 742 in the 2011 Census.
Cilymaenllwyd is a bilingual community with 53% of people aged 3 years and over able to speak, read or write Welsh.