Persia is the greatest empire on Earth, stretching as far east as the Indus River. Though it has internal problems it remains the greatest threat to the the Greek way of life. Persia has several times tried to absorb Greece but has always been repelled. It occupies much of Anatolia and threatens the few Greek cities which remain free.
The current emperor is Artaxerxes II who rules from the great city of Babylon, home to the famous Hanging Gardens. The empire is divided into satrapies, semi-autonomous states that pay tribute to the Emperor and receive his protection in return. These conquered nations are allowed to keep their own ways and laws as long as they don't revolt. Ruling satraps are appointed by the Emperor and are often local royalty who have surrendered to Persian rule.
Between the satraps and the Emperor is the civil service. This powerful body consists of thousands of scribes, tax collectors and officials who run the empire day to day. They are aided by a vast web of roads which carries messengers, taxes and soldiers at great speed from region to region.
As well as the direct military threat Persia poses to Greece it sows discord by meddling in Greek politics. The Spartan Hegemony ended when Corinth, Thebes and Athens revolted, but these revolts were funded by Persian gold. Artexerxes did this to distract Sparta from an invasion of Persian lands in Anatolia. It was an effective strategy and has kept Greece from being fully united under Spartan rule. In recent years, Persian influence can be seen by the adoption of their ways into Greek culture. Athenians with their strong trade links to Persia are the leaders in this cultural shift.
An empire as large as Persia always has internal threats as well as international ones. A rebellion is growing in the satrapy of Cappadocia in Anatolia. The satrap, Datames, was a respected general sent to reconquer Egypt but machinations in the Emperor’s court forced him into rebellion. He took his army to Cappadocia and is trying to rally support. This war and the rebellion in Egypt has created the greatest moment of weakness the Empire’s enemies can expect for a long time. Artexerxes has abandoned any hope of invading Greece as a whole and now focuses on political interference.
Persia is able to raise a million man army from across the Empire. Tactically they rely on massed ranks of archers behind shield walls to whittle down their enemies. Persia breeds the finest horses in the world and their sophisticated metalwork allows them to field frightening cataphracts. These heavily armoured men and horses thunder across the battlefield to exploit weaknesses made by the archers. The only foot soldiers of note are the Immortals, the personal troops of the Emperor. There are exactly ten thousand of them and they are skilled in archery and with the spear. Their presence on the battlefield can show the Emperor's personal interest and their fearsome reputation is well deserved.
Religion and Culture
Persians are unusual and recognise only one god: Ahura Mazda, the "Bringer of light, wisdom and truth." He is the creator spirit, source of truth and order in the world, worshipped through fire and with a flame as his symbol. Telling the truth is a religious duty for his worshippers and liars have been killed as heretics.
The lone god created seven lesser beings known as spenta to serve him. They appear as brilliant lights and are seen at the borders of the empire, acting as protector spirits. Persians also believe in a trickster spirit named Angra Mainyu. He is the antithesis of Ahura Mazda and the king of lies and chaos.
Neither god or trickster has champions in the way of the Greek pantheon. However, Ahura Mazda did once have a prophet called Zoroaster who walked the Earth a century ago. He was imbued with incredible persuasive power which focused Persian worship on Ahura Mazda. Though long-dead, the order of priests he founded aggressively spread the religion. Conquered lands may not be forced to adopt the religion by the Emperor but most quickly convert when faced with the priests of Zoroaster.
Judea & Levant
The ancient land of the Jews is satrap called Yehud Medinata. Under a Persian governor, the Jews are controlled by a line of high priests ruling through Jewish religious law. The land is fertile with wide coastal plains and highlands further inland, but sparsely populated. The city of Jerusalem houses only a few thousand people and is based around the temple. Most people live in small villages dotted about the land.