Three more kings: The Persian kings who followed Cyrus II were most likely:
Cambyses, who ruled from 530 to 522 BC,
Gaumata, who ruled in 522 BC and was a usurper, and
Darius I, who ruled from 521 to 486 BC.
The fourth was probably Xerxes I, who ruled from 486 to 465 BC (see study note on Esther 1:1). Xerxes was famous for his wealth, his army of 1,700,000 soldiers, and his large navy (see Herodotus, Histories 7.6). He used these forces to fight against Greece, but did not succeed. The Persians could not defeat Greece's growing power. God's guiding hand influenced the historical events in this chapter.