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.
Campaigns of Nader Shah
The Afsharid Conquest of the Persian Gulf was an imperial venture by the Iranian Empire, ruled by Nader Shah, to establish Iran as the hegemon of the Persian gulf and its surroundings. The numerous campaigns that were undertaken were initially very successful and achieved a great many objectives however the rebellion of Nader's appointed Darya Salar (Admiral), Mohammad Taqi Khan, wreaked havoc amongst the plethora of polities across the Persian gulf that had been brought under Iranian control and even after the defeat and capture of Mohammad Taqi Khan the Iranian empire was going through a tumultuous period of unrelenting civil strife and internal war due to Nader's increasingly brutal rule which made the empire collapse in the immediate aftermath of his assassination, leading to many of the conquests in the region to be lost.