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.
Iran
From the late 10th to the late seventh century BC, the Iranian peoples, together with the "pre-Iranian" kingdoms, fell under the domination of the Assyrian Empire, based in northern Mesopotamia. Under king Cyaxares, the Medes and Persians entered into an alliance with Babylonian ruler Nabopolassar, as well as the fellow Iranian Scythians and Cimmerians, and together they attacked the Assyrian Empire. The civil war ravaged the Assyrian Empire between 616 and 605 BC, thus freeing their respective peoples from three centuries of Assyrian rule. The unification of the Median tribes under king Deioces in 728 BC led to the foundation of the Median Empire which, by 612 BC, controlled almost the entire territory of present-day Iran and eastern Anatolia. This marked the end of the Kingdom of Urartu as well, which was subsequently conquered and dissolved.
In 550 BC, Cyrus the Great, the son of Mandane and Cambyses I, took over the Median Empire, and founded the Achaemenid Empire by unifying other city-states. The conquest of Media was a result of what is called the "Persian Revolt". The brouhaha was initially triggered by the actions of the Median ruler Astyages, and was quickly spread to other provinces, as they allied with the Persians. Later conquests under Cyrus and his successors expanded the empire to include Lydia, Babylon, Egypt, parts of the Balkans and Eastern Europe proper, as well as the lands to the west of the Indus and Oxus rivers.