Original: The Achaemenid Empire ( c. 550 â '' 330 B.C.E. ) , , also known as the Persian Empire , was the successor state of the Median Empire , expanding to eventually rule over significant portions of the ancient world which at around 500 B.C.E. stretched from the Indus Valley in the east , to Thrace and Macedon on the northeastern border of Greece .
Simplified: The Achaemenid Empire , or Achaemenid Persian Empire , ( 550 â '' 330 BC ) was the first of the Persian Empires to rule over significant portions of Greater Persia ( or Iran ) . It followed the Median Empire as the second great empire of the Iranian peoples .