King of Persia (r.521-486 BC) who ruled the Achemenid empire at the height of its power. He seized the throne after the death of Cambyses and secured the northern frontiers by defeating the Scythians. He conquered the Indus valley and Thrace, but failed to conquer Greece (the battle of Marathon, 490 BC). Darius continued the policy of restoring the Jewish state and contributed to the rebuilding of the Temple at Jerusalem. He also reorganized the empire by establishing a federal system of satrapies, efficient taxation and postal systems, and a new military organization. He built a new capital at Persepolis.