The Indo-European term refers to the whole peoples speaking a common language called Proto-Indo-European, that would have populated a geographical area shared between the middle of the fifth millennium BC and the beginning of the second millennium B.C. This ethnic group would then be dispersed to Eurasia due to complex dynamics of diffusion, connected to lines of transhumance, trade and military dynamics. The most common hypothesis on the type of population was that of a people made up of nomadic warriors who, migrating from its original sites, because of the scarcity of resources, would have overwhelmed the pre-existing civilizations, bringing however technological innovations such as the way to work the bronze, and after that the iron, the use of the war chariot and finally the use of horses. These features are the peculiarities of the Persian armies. Legendary are the military exploits of some of their king, whom Cyrus the Great and Darius. Their victories (on the powerful kingdom of Lydia, for example) are not very often reported, indeed, much often are reconstructed the events that will saw them defeated by the Greek poleis. In fact, the list of Persians achievements is extensive, as well as their domains were wide and large and great were their administrative capacities (the satrapies system). Yet, it is precisely in this structure that we found, on one hand, their great ability to maintain this relatively autonomous subject populations, but we also find the element of the military weakness of the Persian army . A multi-ethnic army, with various military and non-traditionals elements, fighting for a sovereign, to whom perhaps not everyone was absolutely devoted, would not fought as troops far more determined and cemented together by very different ideals. The wars against the Greek poleis will be an example, but the final confirmation will come with the defeats suffered by Alexander, which demonstrate that the Persian army could not be defeated only through the use of topographic factor (the mountainous Greece did not favor the Persian cavalry), but also thanks to the value of the men on the field. But the origin of some basics features that will make the dreaded Persian army there was the influence of one of the most famous Semitic peoples in history: the Assyrians. The scythed chariot, which over the centuries was so much used by the Persian armies seems to have been native of the Assyrians lands, we have source reporting that Nino, king of the Assyrians, had as many as sixteen thousand scythed chariots when they moved to the assault of Bactria. It is however up to Cyrus II of Persia the idea of having transform the chariot in a real weapon, with its tactical organization. The Assyrian army had also at their service units of “engineers” that allowed them to quickly build bridges and boats for crossing rivers, war machines and, seems also that the Assyrians were among the first to introduce horsemen armed with bows. This advanced military force will bring the small city-state of Assur, to win on several occasions, including in the territories of Asia Minor, of the Persian Gulf, in much of Egypt and almost along all the coasts of the eastern Mediterranean. But, unlike the Persians, the lack of administrative organization and the continuing struggles for power, show the fragility of the Assyrian Empire, which will fall quickly under the blows of another Iranian people, the Medes.
The victory of the Babylonian army led by Nebuchadnezzar against the Assyrian-Egyptian joint forces near the city of Carchemish, represent the epic ending of the Assyrian Empire and marks the Neo-Babylonian domain in the Syrian-Palestinian.