List of ancient great powers
The Sassanid Empire is the name used for the fourth Iranian dynasty, and the second Persian Empire (226–651). The empire's territory encompassed all of today's Iran, Iraq, Armenia, Afghanistan, eastern parts of Turkey, and parts of Syria, Pakistan, and large parts of Caucasia, Central Asia and Arabia. During Khosrow II's rule in 590–628 Egypt, Jordan, Palestine, Lebanon were also briefly annexed to the Empire, as well as far west as western Asia Minor. The Sassanid era, encompassing the length of the Late Antiquity period, is considered to be one of the most important and influential historical periods in Iran. In many ways the Sassanid period witnessed the highest achievement of Persian civilization. The empire is furthermore known for being the arch-rival of the neighboring Roman–Byzantine Empire for a period of over 400 years. As the Parthians were replaced by the Sassanids, they carried on the already century long lasting Roman–Persian Wars, which would eventually become the longest conflict in human history.
Prehistory of Iran
Records become more tangible with the rise of the Neo-Assyrian Empire and its records of incursions from the Iranian plateau.
As early as the 20th century BC, tribes came to the Iranian Plateau from the Pontic–Caspian steppe. The arrival of Iranians on the Iranian plateau forced the Elamites to relinquish one area of their empire after another and to take refuge in Elam, Khuzestan and the nearby area, which only then became coterminous with Elam. Bahman Firuzmandi say that the southern Iranians might be intermixed with the Elamite peoples living in the plateau.
By the mid-first millennium BC, Medes, Persians, and Parthians populated the Iranian plateau. Until the rise of the Medes, they all remained under Assyrian domination, like the rest of the Near East. In the first half of the first millennium BC, parts of what is now Iranian Azerbaijan were incorporated into Urartu.