Judging by the genealogical references, Coel Hen must have controlled a large part of the Hen Ogledd. As an ancestor figure, he compares to Dyfnwal Hen, who is likewise attributed with founding kingly lines in the Hen Ogledd. Hector Boece and Ayrshire folklore both state that Coel and his entire army perished in the Battle of Coilsfield. According to Welsh tradition the region of Kyle was named for Coel, and a mound at Coylton in Ayrshire was regarded as his tomb. Projections back from dated individuals suggest that Coel Hen lived around AD 350–420, during the time of the Roman departure from Britain. In his book "The Age of Arthur", historian John Morris suggested Coel may have been the last of the Roman "Duces Brittanniarum" (Dukes of the Britons) who commanded the Roman army in northern Britain, and split his lands among his heirs after his death. However, Morris's book has been widely criticized. It has been suggested that Coel was appointed governor of northern Britain, ruling from Eburacum (York), by Magnus Maximus.