Note:  Do not rely on this information. It is very old.

Darius I

Darius I., King of Persia, son of Hystaspes, ascended the throne after the death of the usurper Smerdis, 521 B.C., and in the belief that his life was in danger, caused Intaphernes, one of seven conspirators who had effected the death of Smerdis, to be put to death. After this he reigned supreme, and turned his attention to the consolidation of his empire, uniting himself by marriage with the royal house, and making Susa his capital. After suppressing numerous revolts and dividing the empire into twenty satrapies, he turned his mind to enlarging his dominions, the confines of which he advanced to the Caucasus and Indus, but in 515 B.C. he signally failed in an expedition against the Scythians, losing 80,000 men. Thrace having been conquered by his general, Megabazus, after an interval of peace Darius carried out his probably long-cherished plan of an invasion of Greece, and crossed the Hellespont, but suffered a signal defeat at Marathon 490 B.C. He died 485 B.C., when a rebellion in Egypt was in full force, and during preparations for a third invasion of Greece.