The Persian Empire was made up of many kingdoms, but Cyrus the Second united them all in to one big kingdom. The empire he reigned over was the biggest empire at the time, it reached from Asia Minor to India, and lasted from 559 to 530BC!
Achaemenes was the first king of Persia,and began building the temple of Parsumash. He was succeeded by Teispes, Cyrus the First, and Cambyses the First. After Cambyses died, Cyrus the Second or Cyrus the Great become king over Persia.
Herodotus, one of the great Greek historians, said that Cambyses had a dream and wanted to kill his son, Cyrus, to prevent him from taking the throne. Cyrus made it out of the palace alive, and some famers took him in to their family. When he was a bit more grown up he worked as a shepherd, his grandfather recognized that it was Cyrus as he was going on a trade route. His grandfather was the king of Media and knew the he was heir to the throne of Persia. So he helped Cyrus return to Persia. And then Cyrus became king.