Over time, in the middle of the second millennium BCE, Indo-Iranian tribes, namely the Persians, entered the Iranian plateau and settled in the southern and eastern parts of the Zagros Mountains, behind Elam's eastern borders. After centuries of settlement and utilizing the political situation of the region, they gradually, and seemingly without severe military confrontations, entered the land of Anshan. Anshan, which formed the eastern territory of the Elamite government and was surrounded by Persians from the north and east, witnessed from the very beginning the interaction of this immigrant tribe with the ancient Elamite state.
The presence of the Persians in Elam's vicinity and their subsequent dominance over the land of Anshan paved the way for complex political and military relations between these two peoples. Frequent Assyrian invasions against Elam, which intensified during the 8th and early 7th centuries BCE, led to the establishment of friendly relations between the Persians and the Elamite state in the form of political-military alliances to counter the common Assyrian threat. This cooperation demonstrates the Elamites' utilization of Persian military capabilities against Assyria.
Furthermore, the presence of the Persians in the vicinity of the Elamites, and later their dominance over the land of Anshan, resulted in the Persians being greatly influenced by Elamite statecraft and culture. For example, Cyrus II adopted the traditional title of "King of Anshan," which was used by the Elamites. Also, in the Persepolis reliefs, the similarity between Persian daggers and Elamite military equipment is evident, and even Cambyses, son of Cyrus the Great, participated in the New Year celebration in Babylon wearing Elamite attire. This indicates the profound influence of Elamite culture and governance on the Persians.
The first reports of an alliance between the Persians and Elam date back to the time of Shutruk-Nahhunte II (717 – 699 BCE). Subsequently, to counter Assyrian influence, these alliances expanded between Elam, the Persians, and other regional powers. For instance, in 691 BCE, Sennacherib, the king of Assyria, claimed to have defeated the Elamite army along with its allies, among whom were the Persians, in the Battle of Halule. These evidences suggest that the Persians established friendly relations with the Elamites from the outset and participated multiple times as allies of the Elamite state in wars against the Assyrians.
Sources continuously speak of Cyrus I's cooperation with the Elamites during the war between Shamash-shum-ukin, the ruler of Babylon, and his brother Ashurbanipal. Additionally, Assyrian sources report the retreat of the Elamite king Humban-nikash with men from the land of Parsuash and also mention the connection between the Persians and Elam during the time of Tammaritu, who summoned troops from the region of Hidalu and Parsuash for war against Assyria. These documents emphasize the important role of the Persians in Elam's foreign policy against Assyria and the Elamites' use of Persian military power and experience against Assyria.
Although we are somewhat aware of the establishment of relations between the Persians and Elamites through Assyrian sources, we do not have much information about the exact time of the Persians' arrival in Anshan and its conquest. The first mention of the Persian presence in Anshan can be inferred from the claim of Cyrus I and a cylinder seal found in Persepolis, in which Cyrus I used the title "Cyrus, King of Anshan, son of Teispes" for himself. Subsequently, Cyrus II (Cyrus the Great) also claimed in his famous cylinder that his ancestors had been kings in Anshan for three generations before him, from the time of Teispes.
It seems that the Persian rule over Anshan occurred gradually and peacefully, and this transfer of power in Anshan did not significantly disrupt previous friendly relations. It even appears that the Persian rule over Anshan, like Cyrus the Great's victory over Astyages, was interpreted as a transfer of power rather than a violent conquest. Perhaps this is why, until the time of Cyrus the Great, the Persian rulers of Anshan used the title "King of Anshan" instead of "King of Parsa," and these friendly relations with Elam continued.