The early history of Wessex in the "Chronicle" has been considered unreliable, with duplicate reports of events and seemingly contradictory information. David Dumville has suggested that Cerdic's true regnal dates are 538–554. Some scholars suggest that Cerdic was the Saxon leader defeated by the Britons at the Battle of Mount Badon, probably fought in 490 (and possibly later, but not later than 518). This cannot be the case if Dumville is correct, and others assign this battle to Ælle or another Saxon leader, so it appears likely that the origins of the kingdom of Wessex are more complex than the version provided by the surviving traditions.