A cantref was a medieval Welsh land division, particularly important in the administration of Welsh law.

Cyfraith Hywel, also known as Welsh law, was the system of law practised in medieval Wales before its final conquest by England. Subsequently, the Welsh law's criminal codes were superseded by the Statute of Rhuddlan in AD 1284 and its civil codes by Henry VIII's series of Laws in Wales Acts between 1535 and 1542.