 Complete the following phrase:  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 512511 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 Is 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 499493 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 