Ancient Macedonian army at 4,500, asserting it was closer to 5,100 horsemen. The army led by Alexander the Great into the Persian Empire included Greek heavy infantry in the form of allied contingents provided by the League of Corinth and hired mercenaries. These infantrymen would have been equipped as hoplites with the traditional hoplite panoply consisting of a thrusting spear ("doru"), bronze-faced "hoplon" shield and body armour. In appearance, they would have been almost identical to the hypaspists. In battle, the Greek hoplites had a less active role than the Macedonian phalangites and hypaspists. At Gaugamela, the Greek infantry formed the defensive rear
Thracian warfare tribal wars also kept Thrace from becoming a major regional power due to the lack of a central government. At the onset of the Peloponnesian War, the Thracian tribes were united under the rule of Sitalces, king of the Odrysae. It was allied with Athens during the conflict. However, the kingdom was again split into different parts after the death of king Seuthes. It was during this time when Philip of Macedon conquered a large swath of Thrace, absorbing the territory and its tribes into Macedon. The "Odrysian kingdom" (Ancient Greek, "Βασιλεία Όδρυσων") was a union of Thracian tribes that