When people talk about the eastern Roman empire, they say that it did not fall until 1453.  However, when the Venetians sacked Constantinople in 1204, they replaced the government so that the Byzantines were out of power for decades.  Why, then, is 1204 not considered the date of the “fall” of the empire, and then the later recapture a kind of “Neo-Roman” or “Neo-Byzantine Empire”?Perhaps a way around this is that while Constantinople fell, the Venetians installed their own emperor in place of the Byzantine one.  So in that sense, there was continuity.  It should be noted, however, that it seems incorrect to say that the Byzantine Empire endured from the beginning of Rome until 1453.