In 539 B.C., Cyrus the Great, the Great King and Founder of the Persian Empire, upon liberation of the people of Babylon, he honored humanity with his declaration of Human Rights and his Persian Empire was called Iranian Empire, meaning the Land of Nobles or the Land of Free.

As inscribed on the cylindrical tablet remained from him and it is now kept in the British Museum (shown below), Cyrus the Great declared that,

"... Everyone in his Empire is free to worship any God he/she wishes to worship, no one is allowed to take anyone as a slave, everyone should be paid accordingly and fairly for the job they are hired to do, everyone has the right to choose their way of life..."

Thus anyone who believes in these principals is an Iranian.

Although No'Ruz was celebrated for thousands of years by the people of Persia, however the Iranian calendar in the honor of the Founder of the Persian Empire begins  with the year he united the lands of Anshan and Sushan  and founded the Persian Empire in 559 B.C.