This revelation begins at the same place as the vision of the ram and the goat in chapter 8. It begins with the second kingdom of Nebuchadnezzar's image (ch. 2) and with the second of the four beasts (ch. 7), namely, Medo-Persia.
Daniel learned that three more Persian kings would arise after Darius (Cyrus, cf. 10:1). Historically these proved to be Cambyses, Pseudo-Smerdis (also known as Gaumata and Bardiya), and Darius I. The fourth Persian king to appear did become stronger than his predecessors and attacked Greece. He was Xerxes I (Ahasuerus).406Xerxes attacked Greece in 480 B.C. with a huge army, but he suffered defeat and never recovered.407
"After his [Xerxes'] great army (estimated by Herodotus at a million men) had subdued virtually all of Greece down to the Isthmus of Corinth and the city of Athens had been reduced to ashes, Xerxes' navy was thoroughly worsted by the united Greek fleet at the Battle of Salamis in 480 B.C. This unexpected setback prompted him to beat a hasty retreat to Asia. The one-hundred-thousand-man land army he left behind under the command of Mardonius was completely crushed in the following year by the allied forces of the Greeks at the battle of Plataea."408