Persia - Carter

Spanning from the Indus River Valley to the Thracian Peninsula in Greece, and boasting the most unified political and economic that any civilization had been able to develop up to that point, the achievements of the Persians are nothing to be scoffed at. During its two century existence, the Achaemenid Dynasty managed to rise from a small family hailing from an obscure corner of modern day Iran, to the rulers of the world's foremost superpower. In order to accomplish this, they established several essential foundations to their empire

First, as the saying goes, they divided and ruled. They split the empire up into twenty different satrapies, which were essentially vassals states ruled by relatives or loyal followers of the Achaemenids, who possessed some degree of autonomy, especially as distance from the administrative center of the empire increased, but still expected to provide tribute to the king in the form of precious metals, militias and levies in times of war, or other valuable resources. Thus, they were able maintain a relatively high degree of stability, despite the vast amounts of land and disparate groups of people that they ruled over.

Secondly, they provided a cultural link in order to establish a common bond between these diverse peoples in the form of Zoroastrianism. In a time when religion was still mostly regional and poorly organized, Zoroastrianism was the first truly state-sponsored religion in a major empire. With this common ground in the form of religion, the Persians were able to unite in the worship of Ahuramazda, ultimately providing much legitimacy to the king, and further ensuring the stability of the realm.

Then, there were the Greeks. As a fiercely independent people, the only people the Greeks liked fighting more than other Greeks, was the Persians. At Marathon, and again at Salamis, the Greeks proved that they would unify against foreign threats, and that they were nothing to be trifled with militarily. Furthermore, Greece was a mountainous land, with little in terms of natural resources, so the Persians stood to gain little from its conquest. With already the greatest empire the world had seen, what reason did the Persians have to waste their time with those stubborn barbarians of the west?