This may have been asked before, but what is the last possible POD for a surviving Western Roman Empire? By 'surviving' I mean a WRE that manages to last into at least the tenth century, albeit probably with various changes in fortune (if it's initially just limited to Italia and perhaps parts of Gaul and Hispania that is fine). In particular, I'm looking for something post 300 AD.
Any ideas?
Amitiés,
Endymion