The Cantref of Penfro was one of the seven cantrefi of the Kingdom of Dyfed. It subsequently became part of Deheubarth in around 950. It consisted of the long peninsular part of Dyfed south of the Eastern Cleddau and the Daugleddau estuary, and bordered on its landward side by Cantref Gwarthaf. The name, meaning "land's end", derives from Pen and "fro". Its area was approximately 140 square miles (360 km2).