They're both right? I was right twice? Right, so the Persian Achaemenid or Achaemenid dynasty was founded in 539 BCE by King Cyrus the Great. Cyrus took his nomadic warriors and conquered most of Mesopotamia, including the Babylonians, which ended a sad period in Jewish history called the Babylonian Exile, thus ensuring that Cyrus got great press in the Bible. But his son Darius I was even greater. He extended Persian control east to our old friend the Indus Valley, west to our new friend Egypt, and north to crash-course newcomer Anatolia. By the way, there were Greeks in Anatolia called Ionian Greeks who will become relevant shortly.