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, during the 2nd millennium CE, the Iranian peoples would play a prominent role during the age of Islamic expansion and empire. Saladin, a noted adversary of the Crusaders, was an ethnic Kurd, while various empires centered in Iran (including the Safavids) re-established a modern dialect of Persian as the official language spoken throughout much of what is today Iran and the Caucasus. Iranian influence spread to the neighbouring Ottoman Empire, where Persian was often spoken at court (though a heavy Turko-Persian basis there was set already by the predecessors of the Ottomans in Anatolia, namely the Seljuks and the Sultanate of Rum amongst others) as well to the court of the Mughal Empire. All of the major Iranian peoples reasserted their use of Iranian languages following the decline of Arab rule, but would not begin to form modern national identities until the 19th and early 20th centuries (just as Germans and Italians were beginning to formulate national identities of their own).