Marcher lordship in southwest Wales, south of the River Teifi and southeast of Cardigan.
It lay on the northern edge of the Marcher lordships of the southwest, and so was liable to attack and seizure, but the power of the March was too strong for it to revert to Welsh rule for any length of time.
It was held by the Marshal Earls of Pembroke. After their extinction in the male line in 1245 Pembroke and Cilgerran went their separate ways, but were reunited in the later 14th century.
In 1536 Cilgerran became part of northern Pembrokeshire.