Darius II ruled from 424 to 404 B.C. When schoolboys used to learn Greek, the usual first text read was Xenophon's Anabasis, which begins: "Darius and Parysatis had two sons, of whom Artaxerxes was the elder and Cyrus the younger..." This Cyrus the Younger was Xenophon's hero in the first book of the Anabasis but was killed in the battle of Cunaxa in the fall of 401 fighting his brother.
Darius was defeated by Alexander three times. Eventually he was murdered by his own people, which was considered unnecessary, disrespectful, and bad form.