Amyntas I of Macedon

In 513 BC, Persian forces led by Darius I crossed the Bosporus in a successful expedition against the Scythians, securing a frontier on the Danube in the process. Darius then returned to Sardis in Asia Minor and ordered his cousin Megabazus to conquer the rest of Thrace. Megabazus marched westward into the Strymon Basin in 512 or 511 BC, subjugating a number of tribes along the way, including the Paeonions, whom he had deported to Asia.[11] Amyntas may have taken advantage of this power vacuum by crossing the Axios River and seizing their former territory around Amphaxitis.[12]

In keeping with Persian practice, Megabazus dispatched seven envoys around 510 BC to meet Amyntas, most likely at the palace in Aegae, to demand "earth and water."[11] Although the exact meaning of this request remains unclear, it appears that Amyntas met Megabazus' demands and invited the envoys to a feast.[13] The Persians, according to Herodotus, requested the company of women after dinner, which Amyntas agreed to despite Macedonian customs. The women, identified as "concubines and wedded wives," sat across the table at first, but moved next to the envoys at their insistence. Flushed with wine, they began to fondle the women, but Amyntas remained silent out of fear of Persian power.[14]

Alexander, enraged by their actions, asked his father to leave and let him handle the situation. Amyntas advised caution, but eventually left, and Alexander sent the women away as well, assuring his guests that they were only washing themselves. In their place, "beardless men" disguised as women and armed with daggers returned to the party and murdered all seven envoys. The Persians began looking for the missing embassy, but Alexander covered it up by marrying his sister Gygaea to the general Bubares and paying him a large bribe.[15]

Modern historians are generally skeptical of the veracity of this story. It could have been fabricated by Herodotus to illustrate Alexander's cunning personality, or he could have simply repeated what he heard while visiting Macedonia.[13] Furthermore, Amyntas, no matter how weak or foolish, is unlikely to have entrusted such a delicate diplomatic situation to his young son.[11] Gygaea's marriage to Bubares is recognized as historical; Amyntas most likely arranged it himself or Alexander handled it after his father's death.[10]

Historian Eugene Borza argued that by rejecting the murder of the Persian ambassadors, there is no longer any evidence that Macedonia was a vassal-state during Amyntas' reign.[11] In accordance with this argument, Mardonius, not Megabazus, would actually subjugate the Macedonians in 492 BC.[13] Nicholas Hammond, on the other hand, asserted that Macedonia remained a loyal subject as part of the satrapy of Skudra until the Persian defeat at Platea in 479 BC.[16]

Amyntas was the first Macedonian ruler to have diplomatic relations with other states. In particular, he entered into an alliance with Hippias of Athens, and when Hippias was driven out of Athens he offered him the territory of Anthemus on the Thermaic Gulf with the object of taking advantage of the feuds between the Greeks. Hippias refused the offer and also rejected the offer of Iolcus, as Amyntas probably did not control Anthemus at that time, but was merely suggesting a plan of joint occupation to Hippias.[17]