Annales Imperatorum Romanorum — SPQR Dashboard

Author's Note

I'm Ermald Billa, and I love history. I built this dashboard to answer a question I had been asking myself for years: where did the rulers of Rome really come from? History books present the emperors in a linear succession, but they hide the geographic dimension of power. By collecting 159 historical figures and cross-referencing them with their region of origin, a clear pattern emerged: Italy dominated the first century, the Balkans saved the empire in the third, and the East carried it on for another thousand years. This is not a story about Rome — it is a story about how power moved away from Rome.

The Illyrian Phenomenon

In 235–285 Illyricum produced 35% of the emperors (8 out of 23) and, across the whole dataset, 23% (36 out of 159), saving the empire in the third century. Diocletian, Aurelian, Constantine: all from the Balkans.

The Shift of Power

Italy (1st c.) → Illyricum (3rd–4th c.) → East (5th–15th c.). The geography of power changed radically over fifteen centuries.

1,480 Years

The longest empire in Western history. The period 235–285 (Third-Century Crisis) saw 23 emperors and usurpers in 50 years — roughly one every two years.

A Third Category

Legitimate/Usurper is a modern dichotomy. Emperors like Diocletian or Basil I were "usurpers" who became founders of eras.

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Emperors

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Legitimate

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Usurpers

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Average Reign (years)

Geographic Distribution of Power Over Time

Emperors by region of origin, per 50-year period. It reveals the structural shift of power over the centuries.

Length of Reigns

Years of reign per emperor (active filter). Green: legitimate · Amber: usurper · Blue: contested.

Legitimate

Usurper

Contested

Chronological Timeline — Gantt Chart by Dynasty

Colour by dynasty Hover for details · Dashed bars = usurpers

Critical Notes on the Dataset

The problem of legitimacy

Labelling an emperor as an "usurper" often reflects the point of view of the winning sources. Diocletian, Aurelian and Basil I the Macedonian were technically usurpers, yet they are among the empire's greatest reformers. The category is anachronistic: in the Roman world, legitimacy was built through victory.

Chronological uncertainty (235–285)

The dates of many emperors of the Third-Century Crisis are estimated with margins of months or years. Primary sources are patchy and often contradictory. Treating these data as precise to the year is historically ill-advised.

The Rome/Byzantium boundary

The continuity between the Roman Empire and the Byzantine Empire is a modern historiographical construct. The emperors of Constantinople considered themselves Romans, not Byzantines — a term coined by historians of the 16th–19th centuries. The "fall" of 476 AD was almost irrelevant for the East.

Missing emperors

Some official co-emperors (Caesars) such as Crispus and Constantius Gallus are not included. Many local pretenders of the third century had very brief reigns and are documented only through isolated coins. The declared completeness of "98–99%" is an estimate, not an academic certainty.

Further Reading