Succession.
There were several Persian leaders called Darius - they were kings of Persia.
Darius and Xerxes.
There were three kings named Darius. Which one do you mean?
The Persian Empire.
king Cyrus and king darius
the two great kings where cyrus, cambyese, and darius.
A monarchy.
Cyrus the Great and Darius the Great.
A standing army known as the Immortals
Their kings, first Darius, then his son Xerxes.
Darius the Great and Xerxes the Great.
Darius the Great and Xerses the Great