Running over much of the English-Welsh border, Offa’s Dyke is a massive earthwork that is a high as eight feet in some places. Historians have long believed that Offa’s Dyke was built in the late eighth-century, but new evidence suggests it might be 200 years older.
Archaeologists from the Clwyd-Powys Archaeological Trust used radiocarbon dating on a stretch of the dyke that shows it was built between 430 and 652, with the most likely date being sometime during the second half of the sixth-century.
The general consensus up to now was that dyke was built by King Offa of Mercia, who ruled between the years 757 to 796. The Anglo-Saxon historian Asser wrote around the turn of the ninth-century that “there was in Mercia in fairly recent time a certain vigorous king called Offa, who terrified all the neighbouring kings and provinces around him, and who had a great dyke built between Wales and Mercia from sea to sea.”
Paul Belford, director of the Clwyd-Powys Archaeological Trust, stated, “This is a tremendously exciting discovery which means we must re-think some of our assumptions about this important monument. Certainly the dyke was built to make a statement about the power of the kingdom of Mercia.”
Offa’s Dyke runs 285 kilometres and in the Early Middle Ages marked the border between the Anglian kingdom of Mercia and the Welsh Kingdom of Powys. Last summer a portion of the earthwork was intentional damaged, and the archaeologists made their examinations there. They now hope to explore other ares of the dyke to see if they also might date from an earlier period. It is now used a popular walking trail.
“It is now likely that parts of the dyke system was in place before Offa’s time but it is also likely that he would have consolidated the existing network into what we now call Offa’s Dyke,” Mr Belford added. “It is now clear that it was not the work of a single ruler but a longer-term project that began at an earlier stage in the development of the kingdom.”