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.
History of Iran
From 334 BCE to 331 BCE, Alexander the Great, also known in Avestan as "Arda Wiraz Nâmag" ("the accursed Alexander"), defeated Darius III in the battles of Granicus, Issus and Gaugamela, swiftly conquering the Persian Empire by 331 BCE. Alexander's empire broke up shortly after his death, and Alexander's general, Seleucus I Nicator, tried to take control of Iran, Mesopotamia, and later Syria and Anatolia. His empire was the Seleucid Empire. He was killed in 281 BCE by Ptolemy Keraunos.