 In the nineteenth and early twentieth centuries Anglo-Saxon weapons and burials were found, and the dyke was thought to have been built in the seventh century as a defence of the Kingdom of East Anglia in its wars with Mercia.An excavation in 1991 established that it had been built in several phases, the first between 330 and 510, and the last between 450 and 620.It is now believed most likely to have been built by early Anglo-Saxon settlers in the fifth century as a defence against Romano-British attempts to recover their territory.