After the occupation of the Lydian kingdom by the Persians, at the end of the 6th century, the cities of Ionia became taxpaying tributaries of the Persians, who installed tyrants as deputies for their power. The Ionian cities apparently continued to flourish, as being the natural outlet for the hinterland of Asia Minor. But it may have been the taxes imposed by Darius in order to finance his Scythian expedition and the restructuring of the empire, as well as the government of the tyrants, that provoked discontent among the inhabitants of Ionia. Aristagoras tyrant of Miletus is said by Herodotus to have worked on the satrap Artaphernes to take advantage of an invitation from the aristocrats on Naxos to occupy the island. But his fear of the consequences of failure in this operation led him to convene, in the spring of 499 B.C., a general assembly of the Hellenic cities of western Asia Minor. At this congress the representatives of the Ionian cities declared a revolt, at the same time dissolving the tyrant regimes.