Oof, the anachronistic nature of this history is immediately relevant when the Huns are being used as a catchall term for nomadic steppe peoples in an era when this is dominated by Indo-European tribes and referred to as the Mongolians. A quick scroll confirms that there's no mention of any indigenous peoples in the Americas, period, even as they're touting the great and mighty power of the, uh, Lombards. You get other Eurocentric gems, like Charlemagne being the most powerful ruler in his time, more so than the contemporary Tang dynasty in China or the Abbasid Caliphate, which... yeah, no that ain't right. Also interesting that Napoleon at his height looks to be ⅔ the power of the British Empire at the time?<p>But more than poking fun at the specific issues in this attempt (and there are many to be sure), I strongly suspect that there's no way to even responsibly attempt such an endeavor. Quantitative data is simply lacking for much of history. Population demographics for well-attested areas such as the Roman Empire at its height is difficult to establish, but if you try to apply it to, say, pre-Columbian North America, the estimates vary by orders of magnitude. GDP estimates are even worse--even today, there are many countries where GDP may be over 25% off, and any number before 1500 may as well be pulled out of an ass.<p>The bigger question is if it's even reasonable to attempt to condense "power" into something quantitative. Economic power doesn't necessarily lend itself to diplomatic power: the US became the world's largest economic power sometime in the late 19th century, yet it remained a diplomatic lightweight pretty much until the climax of WWI.