If you consider the so-called Byzantines to be Romans (and you should, for lots of reasons), the Roman state was at least a notable regional power all the way from the mid 300s BCE all the way up to 1204 - that's around 1500 years. And it existed for a few hundred years more on either end.
I remember someone (maybe Tamim Ansary?) writing that states that claimed to be the direct successor of the Roman Empire existed until 1922, at least in the sense that the Ottoman Empire used some titles and administrative terminology of the Byzantine Empire.
> After the conquest of Constantinople in 1453 by Mehmed II, Ottoman sultans came to regard themselves as the successors of the Roman Empire, hence their occasional use of the titles caesar (قیصر qayser) of Rûm, and emperor, as well as the caliph of Islam.
which used that term after a break of several centuries (so not very continuously with the ancient Roman Empire). But Germans then claimed to be Roman emperors (in some sense) until 1806!
These aren't as continuous with the ancient Roman empire as the Byzantines, but it's still pretty astonishing to think that various monarchs were still claiming to be (in at least a theoretical legal sense) Roman emperors during the 1800s and 1900s.
Also the Czars of Russia. The Romanovs were descending from the niece of the last Byzantine Emperor (Sophia Palaiologina niece of Constantine XI).
So you are right that WWI can be argued to the real end of the Roman Empire!!!
One of these days I am going to a series on “When did the Roman Empire End?” Currently, I have at least 10 plausible dates/events. It turns out to be a very interesting overview of a lot of events and characters in Western History.
Unfortunately, Putin still occasionally invokes Russia as the successor to the Eastern Roman Empire in an attempt to justify his imperial ambitions, so we're still riding this train.
There is a Russian name for Istanbul - Царьгра́д (Tsargrad). The relevancy of this traditional name in our time can be glimpsed from the media org tsargrad.tv , a Russian equivalent of fox news.
It's not just a Russian name, it's the Slavic name for Constantinople. It's used in all Slavic-speaking countries when teaching Byzantine history, of course, written with slight distortions depending on the Slavic language in question
Truly boggles the mind.