After Darius I of Persia () launched a military campaign against the Scythians in Europe in 513 BC, he left behind his general Megabazus to quell the Paeonians, Thracians, and coastal Greek city-states of the southern Balkans. In 512/511 BC Megabazus sent envoys demanding Macedonian submission as a vassal state to the Achaemenid Empire of ancient Persia, to which Amyntas I responded by formally accepting the hegemony of the Persian king of kings. This began the period of Achaemenid Macedonia, which lasted for roughly three decades. The Macedonian kingdom was largely autonomous and outside of Persian control, but was expected to provide troops and provisions for the Achaemenid army. Amyntas II, son of Amyntas I's daughter Gygaea of Macedon and her husband Bubares, son of Megabazus, was given the Phrygian city of Alabanda as an appanage by Xerxes I (), to secure the Persian-Macedonian marriage alliance. Persian authority over Macedonia was interrupted by the Ionian Revolt (499–493 BC), yet the Persian general Mardonius was able to subjugate Macedonia, bringing it under Persian rule. It is doubtful, though, that Macedonia was ever officially included within a Persian satrapy (i.e. province). The Macedonian king Alexander I must have viewed his subordination as an opportunity to aggrandize his own position, since he used Persian military support to extend his own borders. The Macedonians provided military aid to Xerxes I during the Second Persian invasion of Greece in 480–479 BC, which saw Macedonians and Persians fighting against a Greek coalition led by Athens and Sparta. Following the Greek victory at Salamis, the Persians sent Alexander I as an envoy to Athens, hoping to strike an alliance with their erstwhile foe, yet his diplomatic mission was rebuffed. Achaemenid control over Macedonia ceased when the Persians were ultimately defeated by the Greeks and fled the Greek mainland in Europe.