Government of the Islamic Republic of Iran world. The Islamic Republic of Iran created shortly after the Islamic Revolution. The first major demonstrations with the intent to overthrow the Shah Mohammad Reza Pahlavi began in January 1978, with a new, Islam-based, theocratic Constitution being approved in December 1979, ending the monarchy. The Shah fled Iran in January 1979 after large strikes and demonstrations against him and his regime paralyzed the country. Ayatollah Khomeini would return in February of the same year after a long period of exile, greeted in the capital of Tehran by several million Iranians. The final collapse of the Pahlavi dynasty occurred shortly after
Name of Iran "Persia" and "Iran" could officially be used interchangeably. However the issue is still debated today. The name "Irān" is first attested in the Avesta as "airyānąm" (the text of which is composed in Avestan, an old Iranian language spoken in northeastern Greater Iran, or in what are now Turkmenistan and Tajikistan). The Modern Persian word "Īrān" () derives immediately from Middle Persian "Ērān" (Pahlavi spelling: "ʼyrʼn"), first attested in an inscription that accompanies the investiture relief of the first Sassanid king Ardashir I at Naqsh-e Rustam. In this inscription, the king's Middle Persian appellation is "ardašīr šāhān šāh ērān" while