The Roman Emperor Galerius, in his dialogues with ambassadors of the Sassanid Empire, at that time under Shah Narseh, describes that “Rome and Iran are like the two eyes of the Earth,” which for two empires that had been in on and off war since the Roman Republic came in contact with Parthia in the 1st century BC, should surely be a shock to hear.
This rivalry is not to be underplayed either, numerous times both Empires made great efforts to snuff out the other. Notably, the failed campaigns of Mark Antony and Crassus come to mind. Regardless, this shared determination was so strong that even when Rome became Byzantium and Parthia became the Sassanid Empire. they still tried to supplant each other with equal determination.
But this quote, despite centuries of bloodshed for domination, comes as a nod of great respect for the equal importance and status of one Empire to its frenemy. Given this phrase coined by Galerius, I find it interesting to consider, in each era what two nations can be looked at as the “Two eyes of the Earth,” which means two nations that may act as foils to one another but are two of the most powerful in the entire world. Also, these nations’ cultures can define an era.
Granted, this is a flawed premise for a thought experiment but one that may help us rethink the way we consider geopolitical rivalry.
Also to note, I will mainly focus on Europe and the Near East.
Moving to the Middle Ages, I would define the two eyes of the earth as being the “barbarians” who conquered Rome and Iran respectively. Because the way I see it while the Roman and Sassanid Empires were conquered, their conquerors learned much from the empires they disposed of, including knowledge of culture, religion, warfare and governance.
Their respective inheritors I would say are the Islamic Caliphate and the Frankish Empire. At that point, Byzantium was well on its way to decline and was losing considerable power and influence as the years passed. The Umayyad and later Abbasid Caliphate and Franks would define the culture and religion of their regions ever since their foundations, but moreover, they also had a very Roman-Iranian relationship. For example, Emperor Charlemagne and Caliph Harun al-Rasheed would send each other lavish gifts of spices, perfumes and fine silk, which echoes the ancient respect between the two great empires. Plus, in a weird mirroring of each other, they were more concerned with enemies of their religion. The Abbasid was preoccupied with the remnants of the Umayyad Caliphate while Charlemagne contested Eastern Rome for the title of Roman Emperor.
In the 13th century, the Mongol Khanate made itself the only eye of the Earth. Like an unstoppable force of nature Eastern Europe, the Middle East, Central Asia, Iran, China and Northwest India were systematically conquered. Whether they submitted willingly or were put to the sword, city after city, kingdom after kingdom were brought under the Mongol yoke. Before the Khan the ground trembled and to the civilized nations of the world, it appeared as though the judgment of God had come upon them. And all that stopped this army from the steppe was the breadth of the land and the sea. However, I do not mean that the Mongols were a horde of brutish savages that destroyed, absolutely not. The Mongol Empire mastered fluidity, in its governance and warfare. From all the nations it conquered it uniquely was able to learn the best points from each of the civilizations they came across. Their tactics were no doubt brutal but the policy established by Genghis Khan maintained a sense of justice.
Moving onto the Early Modern period the next two great states seem to be the Hapsburg Empire and the Ottoman Empire. Very simply, the Hapsburgs were one of the greatest European dynasties and as the family motto put it “Let others wage war: thou, happy Austria, marry.” Through the Spanish and Austrian branches, the Hapsburg family came to be one of the most influential in the Holy Roman Empire and held great prestige across Europe.
On the other side of the coin would be the Ottoman Empire, rising from the ashes of Eastern Rome, the Ottoman Empire brought vast swathes of the Muslim world under their new Caliphate, and with the vigor typical of new Empires they rose exponentially in wealth and power. Of course, the trajectory of these two great states came ahead at the Seige of Vienna, where the Ottoman military suffered a disastrous defeat at the hands of the Christian League. Things weren’t peachy for the Hapsburgs either; eventually, they lost Spain and were being out-competed by Britain, France and eventually the newly founded German Empire. While both empires had stagnated the colonial and industrial projects of Western Europe bore fruit leaving these two states behind. Poetically, the Ottomans and Hapsburg Austrians shared the same fate of fighting and losing on the same side in WWI.
After this point it and before the 19th century, it gets harder to say that there were only two nations who were on par with each other and coexisted for some time, but succinctly a consistent great power would be the British Empire, first at odds with France until after Napolean, then with Russia, then with the German Empire. Because Europe mostly consisted of powerful, far-reaching or influential empires it’s again hard to just point out two. The same thing applies in WWII.
Coming out of the war, the United States and the Soviet Union emerged as the two eyes of the earth in the most literal sense, as among the entire world they were the two most powerful and influential powers.
Coming into the modern world it’s pretty clear to see that, with the fall of the USSR, the decline of Europe and the new economic alliance forming around BRICS as well as the Belt and Roads initiative, China and the United States are today the two great eyes of the world. The world revolves around Washington and Beijing and with that comes the necessary acknowledgement of one another as a superpower of significant standing on the global stage.