When talking about empires, different ones come to mind: the roman empire, China, the British Empire, all encompassed larges swathes of territories during centuries or more, but they are somehow difficult to compare. I was wondering how the comparison would be if you normalised them.
One simple way to do this is measure them in year-men, i.e. the population multiplied by the length of the empire in time. My calculation are very approximate, taking the mid-point population is probably a very bad approximation for the integral of the population over time, but it is late. This yields the following table:
| Duration | Population (mid-point) | Product | |
|---|---|---|---|
| Han Dynasty | 426 (206 BC–220) | 57’671’400 | 24’568’016’400 |
| Western Roman Empire | 503 (27 BC–476) | 58’800’000 | 29’576’400’000 |
| Tan Dynasty | 289 (618–907) | 65’000’000 | 18’785’000’000 |
| Byzantine Empire | 891 (330–1453) | 9’265’000 | 8’255’115’000 |
| Mongol Empire | 162 (1206-1368) | 100’000’000 | 16’200’000’000 |
| Ottoman Empire | 624 (1299–1923) | 20’769’225 | 12’959’996’400 |
| Qing Dynasty | 268 (1644–1912) | 268’238’000 | 71’887’784’000 |
| Imperial Britain | 99 (1815–1914) | 400’000’000 | 39’600’000’000 |
I find it interesting that empires start at around 10 Giga-person-years (so I should have kicked out the Byzantine Empire). With the exponential growth of population it is not surprising that the two heavy weight empires (Qing Dynasty and British Empire) are closest to the present time.
If we use this metric, if we consider the USA as an empire that started in 1945, then it would have an approximate size of 14’913’164’515 persons-years, in comparison the People’s Republic of China is 49’264’740’000 persons-years.
Interesting. You can expand the concept to any entity (including all countries but companies or any human group too). Finding more accurate population values is only a question of time.
The beginning and the end of an Empire is something very political. Why should America begin in 1945? 100 years before it already claimed domination on all America, although the official borders did not expand much. And the US had more land before 1945 than after (Philippines, Panama…)
For Germany, would you create a single Reich from Otto to Francis II, or to Hitler, or to Merckel? When does a « European » Empire begins?
You could do the same with the surface and compute a ratio ( m2 / person ) of which Empire did use its surface the more effectively :-)
I would value land and overall surface areas as well as (if not above) population, and duration above all. But I think you’re comparing qualitatively different entities: the Roman, Byzantine, and British Empires (to say nothing of Persia, too!) all functioned very differently for different purposes.