The Argead Empire is a formable nation representing the restoration of the Empire of Alexander the Great that had fallen apart just before the start of the game. Its Diadochi successor states of Phrygia, Seleukid Empire, Egypt, Macedon, and Thrace are the best positioned to reform the empire, but the Argead Empire can potentially be created by any Hellenistic culture group monarchy. As an endgame tag in an unofficial "fourth tier" - even other tier 3 formables can create it, if they meet the requirements, it has the most stringent requirements but the greatest rewards of any formable nation in the game. Forming it requires conquering the main cities across every part of the empire, from Macedonia and Egypt to Mesopotamia and all the way to the Indus Valley, but grants claims across almost all of its former territory - about a quarter of the entire map - as well as giving a powerful permanent modifier, including a bonus to Wrong Culture-Group Happiness that makes further conquests and handling aggressive expansion much easier, a fit reward for the heirs of the great conqueror Alexander.
For too long parasites and scavengers have made a feast of the Great Empire that Alexander spent a lifetime building. It is time we do away with all claimants, usurpers and delusional provincial strongmen. There can be only one authority within the empire of Alexander the Great, one upholder of the great Hellenistic legacy that this great man founded.
That one power could not possibly come from any dynasty but our own. Only a family that respects the Argead traditions can legitimately claim its legacy.
Get claims on all unowned provinces in the regions of Parthia, Syria, Ariana, Bactriana, Media, Persis, Gedrosia, Mesopotamia, Assyria, Bithynia, Cappadocia, Galatia, Cilicia, Asia, Greece, Palestine, Gandhara, Lower Egypt, Upper Egypt, Macedonia, and Thrace
Forming the Argead Empire triggers a special event allowing the country to move its capital to either Alexandreia (516), Pella (379), Babylon (918), or Alexandreia Indos (4371), or retain the court at its current position. Each option will give a different bonus to the new capital - choosing the Alexandreia Indos option in particular will also grant claims to all of the region of Madhyadesa.