Persia has long been used by the West to describe the nation of Iran, its people, and its ancient empires. It derives from the ancient Greek name for Iran's maritime province, called Fars in the modern Persian language, Pars in Middle Persian and Pārsā in Old Persian, a word meaning "above reproach". Persis is the Hellenized form of Pars, and through the Latinized word Persia, the other European nations came to use this word for the region.
This area was the core of the original Persian Empire. Most foreigners referred to the state as Persia until March 21, 1935, when Iran formally asked the international community to call the country by its native name; the Aryan tribes who formed the country in the Achaemenid era united the plateau in that region and had called the country Iran at its birth. In 1959, Shah Mohammad Reza Pahlavi announced that Persia and Iran can be used interchangeably.