Byzantine Empire or Eastern Roman Empire?

[Tintrlvr]

I think Eastern Roman only makes sense as long as there was a Western Roman counterpart. 476 is a somewhat arbitrary delineation, but it's fair as the transition. One alternative would be when Heraclius changed the language of official documents from Latin to Greek (which conveniently coincides roughly with the loss of the Levant and Egypt, i.e., to the area that the Byzantines would control for most of their history). You might also consider Justinian's conquests, ironically, as the point of departure.

I don't think it's really reasonable to call the empire "Roman" past the seventh century at the very latest. Even during the classical Roman Empire, there was a clear cultural delineation between the Greek East and the Latin West, a separation that only became more acute with the division of the empire and subsequent decline of the West. And things that had been really defining features of the Roman Empire, such the Senate, were quickly reduced to mere historical quirks in the Byzantine Empire, and even the internal organization of the empire changed dramatically with the emergence of themata. The Christianization of the empire (admittedly, which occurred before the disappearance of Western Rome, although paganism was still quite widespread until the 6th century) clearly dramatically changed the culture from classical Rome, too. There are just too many cultural differences between the Byzantines and the classical Romans, despite the continuation of the name, to call them one and the same.