The Achaemenid Empire ( Xšāça, "The Empire" in Old Persian) was an ancient Iranian empire based founded by Cyrus the Great. Also called the First Persian Empire, it took its name after the royal dynasty who ruled it from 550 to 330 BC, before Alexander the Great's conquest. To make it simple, it was kind of a Roman Empire before there even was a Roman Empire; it also predated Imperial China ushered by Qin Shi Huangdi by more than three centuries.
The empire's history began when a then-obscure population, the Persians, settled in what today is Iran as vassals of the Median kingdom, which at that time ruled Mesopotamia and the Iranian plateau. In few centuries the Persian royal family, the Achaemenides, managed to supplant the Medians and conquered a lot of more ancient and developed civilizations (the Medes, Babylonians, Assyrians, and Egyptians), ruling an empire that was a melting pot of civilizations long before the concept even existed. Quoting Neil MacGregor, the empire at its greatest extent stretched from the Northern Balkans to modern-day Pakistan.
Originally vassals to the Median kingdom, in the sixth-century BC Achaemenid Persians revolted against the Median monarchy, leading Cyrus the Great taking over the throne in 550 BC. The Persians then consolidated their influence over the rest the Iranian region, and assimilated the non-Iranian indigenous groups of the region, the Elamites and the Mannaeans (there's still a region in modern-day southwest Iran named Elam after the former population).
Cyrus the Great deserves his own mention, which is expanded in his page. To sum it up, the founder of the dynasty did accomplish some impressive things, like the four-capital system (the capitals were Babylon, Ectabana, Susa and Persepolis) installing the Ur-Example of feudalism, mean the satrapies (kingdoms and regional entities with moderate autonomy), achieving freedom of cult, organizing a bureaucratic apparat, military conscription and a professional soldiers army (the Immortals unit, 10,000 highly trained soldiers), and last but not least an embrional form of postal system. This system lasted for centuries, retained by the following dynasties of Seleucids, Parthians and Sasanians.
By 546 BCE, Cyrus the Great had defeated Croesus, the famously wealthy Lydian king, and gained control of Anatolia, Armenia, and the Greek colonies along the Levant. On the eastern side, he took Parthia, Chorasmis, Bactria and conquered Babylon, famously releasing the captive Jews, thus earning his immortalization in the Book of Isaiah. The following two centuries would be a race to conquer what was left west of Asia... Ancient Greece.
His successors were less successful. Cyrus's unstable son, Cambyses II, conquered Egypt but died shortly after as the result of either an accident or suicide during a revolt led by a priest, Gaumata, who usurped the throne by pretending to be Cambyses' late brother Bardiya until overthrown in 522 BCE by a member of a lateral branch of the Achaemenid family, Darius I. Darius attempted to expand his interest to mainland Greece for a number of reasons: continental Greece supported rebellious Greek colonies under his rule, and he also wished have total control on the trading in the Black Sea.
The Greco-Persian Wars ensued. After two unsuccessful attempts to invade Greece, the Achaemenid empire started to face internal problems. The imperial court was beset by factionalism among the lateral family branches, something that stuck till the last ruler of the Achaemenids, Darius III, was betrayed and killed by his subjects and kins.
The Achaemenid Empire's society was extensively described by Herodotus. The official language of the empire was Old Persian (the ancestor of modern-day Farsi, the language spoken in Iran, Afghanistan and Tajikistan in different dialects) but Aramaic was the lingua franca thanks to the widespread presence of Semitic peoples (Canaanites, Hebrews, Assyrians...) in the empire. Greek also gained a prominence as a bureaucratic and erudite language even before the Macedonian conquest. Ancient Persian rulers followed Zoroastrianism, one of the first monotheistic religions in the ancient world, but had a tolerant approach to the religion of their subjects, sometimes even paying respect to other prominent deities for good publicity.
The House of the Achaemenides lasted roughly two centuries, due to being a large family with plenty of heirs thanks to royal polygamy. According to Greek historians (who we can assume were a bit biased) they may have been a Big, Screwed-Up Family. Given the amount of kings murdered due to internal plotting, one cannot blame them. Still an intensely entertaining dynasty. Here some useful notes for each of them.
- Achaemenes: the main ancestor of the dynasty, although little is known about him. It is quite possible that Achaemenes was the mythical ancestor of the Achaemenes, but had he existed he would have lived around the end of the 8th century and the beginning of the 7th century BC. He was not yet The High King, just a vassal of the Median kingdom.
- Teispes: Ditto for his father, we don't have much sources about him. Teispes is known to have conquered the Elamite city of Anshan and somewhat expanded his small kingdom. He was succeeded by his second son, Cyrus I.
- Cyrus I: Another nebulous ruler, as we have conflicting notions about him. He was son of Teispes along with his brother Ariaramnes and divided with him the kingdom after their father's death. Little else is known, aside having fought on the side of Ashurbanipal, king of Assyria, in his war against his claimant brother.
- Cambyses I: Known largely for being the below guy's father, Herodotus describes him as "a man of good family and quiet habits". He was married to Princess Mandane of Media, daughter of his overlord Astyages, who is said to have chosen him as his son-in-law because he didn't considered him a threat to the Median throne. His grandson would prove him wrong.
- Cyrus II, the Great (550 — 529 BCE): The punishment for his grandfather's arrogance, it seems. Instead of swearing allegiance to his grandfather, he went along on conquering his kingdom. Upon his victory over the Medes, he incorporated both Median and Persian nobles in his government. He was an example of Young Conqueror, as he took Asia Minor, Drangiana, Arachosia, Margiana and Bactria. Took Babylon and made it one of the capitals of his new empire. He's still revered not only as a great conqueror but also as a shrewd politician who ensured stability (Alexander, we're looking at you).
- Cambyses II (529 — 522 BCE): Traditionally seen as a Sketchy Successor, although he did manage to expand the empire into Egypt by defeating the Egyptian Pharaoh Psamtik III. The throne was then usurped by a man posing as his brother Bardiya, most likely a magus, or a Zoroastrian priest. Cambyses attempted to gain it back, but died shortly either by accident or suicide (or murdered, who knows?).
- Smerdis, the Magian (522 BCE): The Usurper. He ruled the Achaemenid Empire for a few months in 522 BC until he was toppled by Darius the Great.
- Darius I, the Great (522 — 486 BCE): The other great ruler of the dynasty, but sadly not a direct descendant of Cyrus the Great. He was instead from a cadet branch who inherited the throne after the Cambyses/Smerdis mess. He started another mess that were the Greco-Persian Wars (or it was the Greeks who started it, depending on your opinion) with an expedition to punish Athens and Eretria for their aid in the Ionian Revolt. It led to the failure at the Battle of Marathon, but at least he subjugated Thrace, Macedon, the Cyclades and the island of Naxos. Darius strengthened the satrapies, organized a new uniform monetary system, made Aramaic the official language of the empire. He also had roads built and introduced standard weights and measures. He left the empire a better place, if not prosperous.
- Xerxes I (486 — 465 BCE): The guy from 300! And a favorite of fictional portrayals it seems, as he's believed to be the Persian king from Book of Esther. A victim of terrible Hollywood History, as he was not black and was not a God-Emperor (no one from this dynasty was, calling yourself a God would have been blasphemy for Zoroastrians). He was instead a victim of a terrible Hope Spot as he almost subjugated mainland Greece north of the Isthmus of Corinth and wiped out the Spartans at the Thermopylae, until the losses at Salamis, Plataea, and Mycale a year later reversed these gains and the campaign ended in failure. He did manage to suffocate revolts in Egypt and Babylon at least. Murdered by Artabanus, the commander of the royal bodyguard with the help of the eunuch Aspamitres.
- Artaxerxes I (465 — 425 BCE): Another Unexpected Successor as he was the third son. His reign started with the rather unpleasant situation of his father and his elder brother's murders to clean up but ultimately he brought justice killing the culprits. He had no wish of invading Greece again, since it never did them any good. He adopted instead the diplomatic strategy of weakening the Athenians by funding their enemies, no doubt with the intention of spreading instability in Greece. Somewhat deconstructed it led to renewed fighting in 450 BC, where the Greeks attacked at the Battle of Cyprus. This time the Athenians didn't achieve much and peace was agreed among Athens, Argos and Persia in 449 BC. Artaxerxes then offered shelter to the ostracized Themistocles, who was probably his father Xerxes's greatest enemy, and granting him great privileges.
- Xerxes II (425 — 424 BCE): Son and heir of Artaxerxes I. After a reign of forty-five days, he was assassinated in 424 BC by his brother Sogdianus, who in turn was murdered by Darius II.
- Sogdianus (424–423 BCE): As a short a ruler as the brother he murdered, he was the illegitimate son of Artaxerxes I and a concubine. Sogdianus apparently reigned for six months and fifteen days before being captured by his half-brother, Ochus, who rebelled against him. Sogdianus was executed and Ochus was crowned as Darius II.
- Darius II (424 — 405 BCE): Like his father Artaxerxes I he stuck with the strategy of favor one party over another, which was at least extending their unquestioned influence in the Balkans. He funded Sparta's campaign against Athens, so they owed him their victory in The Peloponnesian War. He had quite a dreadful wife, his half-sister Parysatis, which the accounts paint as rather cruel and a major player in their son's reign.
- Artaxerxes II (405 — 359 BCE): An intense reign. Before Artaxerxes II could take to the throne his legitimacy as ruler was threatened by his younger brother Cyrus the Younger, satrap of Asia Minor and their mother's favorite. The Queen mother also had terrible relationships with her daughter-in-law Stateira I, whom she later had murdered. This kicks the plot of Xenophon Anabasis, as the only reason he ever set foot in Persia was that Cyrus the Younger raised an army of Greek sellswords to sustain his coup. Unfortunately for Cyrus, he was killed at the Battle of Cunaxa (meaning he almost made it to Babylon). The success of Cyrus the Younger's revolt (his army was winning up until the point Cyrus died in battle), and particularly the effectiveness of the Greek hoplites he had hired, led certain Greek rulers to realize that an offensive campaign against seemingly-unbeatable Persia actually stood a good chance of success ...
Artaxerxes then became involved in the Corinthian War along with Sparta but as the Spartans had started by invading Asia Minor he funded the Athenians, Thebans and Corinthians instead. The alliance with Athens managed to destroy the Spartan fleet at the Battle of Cnidus (494 BC). Fearing that his Athenian allies were becoming too powerful, he sided again with Sparta betraying his allies and signing the Treaty of Antalcidas, restoring control of the Greek cities in Anatolia and giving Sparta the control on the Greek mainland.
- Artaxerxes III (359 — 338 BCE): Son and heir of Artaxerxes II as well as the first Pharaoh of the 31st dynasty of Egypt. After becoming king, Artaxerxes murdered all of the royal family to secure his position. He also started to butt heads with Phillip II of Macedonia, who was extending his influence in Greece. He long tried to suppress a revolt in Egypt, was defeated by Nectanebo II after a year of fighting the Egyptians, but the second campaign proved to be successful as he deposed the last native Pharaoh. Artaxerxes III was murdered by the ambitious eunuch Bagoas.
- Arses (338 — 336 BCE): Puppet King of Bagoas due to his youth. He lives in the times the Macedonian king Philip II was becoming a real threat as he established a league of Greek city states under his leadership. Arses unfortunately tried to free himself from Bagoas' authority and influence but it allegedly resulted in his murder and the ascension to the throne of his cousin Darius III, the last ruler.
- Darius III (336 — 330 BCE): A very unfortunate ruler. Last king of the Achaemenid Empire, he inherited an unstable empire, governed by increasingly unreliable satraps, a weakened central government. From Bad to Worse, the already ambitious Phillip of Macedonia was succeeded by Alexander the Great, who began his invasion of the Persian Empire in 334 BCE and subsequently defeated the Persians in a number of battles that peaked at the Battle of Gaugamela. Alexander also famously sacked and ravaged Persepolis by fire in 330 BC. After gaining control of the heart of the empire Alexander was set to pursue Darius, who went in hiding. Before Alexander reached him, however, Darius was betrayed and killed by his cousin, Satrap Bessus. Alexander at least avanged his rival punishing the traitor as he deserved. Darius' daughter Stateira was married off to Alexander to create a Greek-Persian royal house, but after Alexander's death in 323 BCE Stateira was killed on Roxane's order, as she was the first wife and pregnant with Alexander's son. So ended the Achaemenid's line for good.
The Battle of Gaugamela cemented the end of the Achaemenid empire. It followed with Alexander the Great seizing Darius III's throne and marrying his two daughters to strengthen his claim. This marks the start of the Hellenistic Empire and the hegemony of Greek culture across the Middle East and North-West India, ending along with it the classical era of Ancient Greece. The Achaemenid empire is still revered as a Golden Age for modern-day Iranians, as they still honor the tomb of Cyrus the Great in Nowruz (the Iranian New Year). Modern day historians tend to agree that the Persian Empire was advanced in human rights, government and culture and less of the tyrannical empire Ancient Greeks sometimes liked to depict (they did attempt to conquer them after all...)