This is an excellent example of a regional locational surname. Whilst arguably of Welsh origin, very few nameholders will be Welsh, but are generally English or even Irish. Locational surnames are "from" names. That is to say names given to people as an easy form of identification after they left a particular place in this case the city of Cardiff, in Glamorgan, to move somewhere else. In fact they have been doing just that for a very long time with early recording examples being William de Cardiff recorded as the canon of St Davids in Wales in the year 1291, and the extraordinary example of William de Karhurdiff, a sort of phonetic spelling, in the Hundred Roll of landowners of the county of Herefordshire, England, in 1272. Curiously as well Wales as a country did not generally adopt hereditary surnames until about the 16th century, some three centuries after England, and the first recording example as shown above is probably a "one off". Other examples showing how the surname became traditionally "English" include John Cardiff of Southampton in the Hundred Rolls of Hampshire also in 1273, and later Ralph Cardiff of Woolfall in the parish of Audlem, Cheshire, in 1612.