 It may be that local people were looking more to their own defence (perhaps influenced by Pelagian thought about self-salvation), as Roman authority waned (for example, taxation-gathering and payment to the troops gradually ceased).In the northern frontier area at least, it looks as though the local Roman fort commander became the local warlord, and the local troops became the local militia operating a local 'protection racket', without any direction from above.This was what Higham called a "return to tribalism", dating perhaps from as early as 350 onwards.