From Coflein:
“This is an ancient standing stone erected (according to tradition) in early British times to commemorate a battle which was fought here between two kings or chiefs, one of whom was named Ifor.
.....
About 1km to the south east of Carreg Maen Taro is the site of two burial cairns called Careg-Croes-Ifor (nprn 405021), presumably the same Ifor mentioned above, and Pen-ffordd-goch (the head of the red road) (nprn 404999), 1.5km to the south east, is said to take its name from a battle waged there; there thus seems to be a vague tradition of a battle fought somewhere in the area.
B.A.Malaws, RCAHMW, 13 October 2006.”