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.
Iranian peoples
Later on, in 550 BCE, Cyrus the Great, would overthrow the leading Median rule, and conquer Kingdom of Lydia and the Babylonian Empire after which he established the Achaemenid Empire (or the First Persian Empire), while his successors would dramatically extend its borders. At its greatest extent, the Achaemenid Empire would encompass swaths of territory across three continents, namely Europe, Africa and Asia, stretching from the Balkans and Eastern Europe proper in the west, to the Indus Valley in the east. The largest empire of ancient history, with their base in Persis (although the main capital was located in Babylon) the Achaemenids would rule much of the known ancient world for centuries. This First Persian Empire was equally notable for its successful model of a centralised, bureaucratic administration (through satraps under a king) and a government working to the profit of its subjects, for building infrastructure such as a postal system and road systems and the use of an official language across its territories and a large professional army and civil services (inspiring similar systems in later empires), and for emancipation of slaves including the Jewish exiles in Babylon, and is noted in Western history as the antagonist of the Greek city states during the Greco-Persian Wars. The Mausoleum at Halicarnassus, one of the Seven Wonders of the Ancient World, was built in the empire as well.