The naming conventions for Persia (aka Iran) changed in 1935. The suggestion for the name change from Persia to Iran is said to have come from the Persian ambassador to Germany, who was a Nazi sympathizer. In 1935 Germany was ruled by Hitler. Aryanism was equated by the Nazis as the highest level of human civilization, in an article of faith based on a vulgar Hegelian hyperbola. Apparently the Persian ambassador was persuaded by his Nazi friends that Persia would be better off as an ally of Nazi Germany. Moreover, he became convinced that the country should be called by its Persian name, Iran, in Western languages. This was to signal a new beginning and bring home to the world the new era in Iranian history, one that would emphasize the Aryan aspect of its people. The name Iran is a cognate of the old word Aryan. The Persian Ministry of Foreign Affairs sent out a memo to all foreign embassies in Tehran, requesting that the country be called "Iran." Unfortunately "Iran" sounded alien to non-Iranians, and many failed to recognize its connection with the historic Persia. Some (Westerners) thought that it was perhaps one of the new countries like Kuwait or Jordan carved out of the ruins of the Ottoman Empire, or like "Pakistan", carved out of India. Even today many confuse Iran with Iraq.

Rez%C4%81_Sh%C4%81h [Wikipedia]

In 1935, the Iranian ruler issued a letter to the League of Nations insisting the name Iran be used instead of Persia. This move had been suggested by the ambassador from Nazi Germany. (The word "Iran" means "Aryan" in the Persian language.)