Iran (earlier known as Persia) has been a crossroads for various groups and empires spreading and then fading over the millennia.
The first real people’s occupying the area we call Iran today were the Median Empire which existed around 600 B.C. This was followed by the Achaemenid Empire (often referred to as the First Persian Empire) between c.550 and 330 B.C.
The Parthian Empire (also known as the Arsacid Empire) existed between 247 B.C. and 224 A.D. and this was succeeded by the Sassanid Empire (Ērān) between 224 and 651 A.D.
The Sassanids hung around for a while, but their territories were eroded by the Arabs and the slow Islamic conquest of Persia. During this period various parts of the territory were also invaded by the Greeks, Turks and Mongols.
Things settled down once more in 1571 when the Safavid Dynasty was established, introducing Shia Islam to Persia. The Safavids were around until about 1722 when they were subject to attack. By 1736 Nader Shah had become the Shah of Iran and he ruled until 1747.
Another period of unrest occurred before the Qajar dynasty was established in 1796; this lasted until 1925 and established the true Shahs of Iran. From a strong start successive rulers proved weaker, and in the late 19th and early 20th Centuries unrest led to a new constitution creating a constitutional monarchy in 1906. The first elections to the Majlis or parliament took place on 7th October 1906.
World War One saw Persia occupied by British and Russian troops, and in 1919 a brief attempt by the British to turn it into a protectorate.
By 1925 the Pahlavi dynasty had been established under Reza Shah who ruled until 1941. The Second World War saw renewed interest in Persia (or rather it’s oil) and it was invaded once more by the British and Soviets in order to secure oil supplies. Reza Shah was forced to abdicate in favour of his son, the more pro-British Mohammad Reza Shah Pahlavi.
Initially the new Shah took a hands off approach to government , but that changed within a few years and by 1978 there were mass demonstrations against the Shah and his government (there had been earlier unsuccessful demonstrations in 1964).
By January 1979 the Shah had fled the country and the exiled Ayatollah Ruhollah Musavi Khomeini returned to mass crowds supporting the revolution. On 1st April 1979 Iran was declared an Islamic Republic.
Ayatollah Khomeini became the Supreme Leader and remained in that role (effectively Head of State) until his death in 1989. He was replaced by Ayatollah Seyed Ali Hoseyni Khāmenei who is the current Supreme Leader.
Iran has had a series of presidents during the years since the revolution. The first president, Abdulhassan Banisadr, was elected in January 1980 but impeached by parliament within months, fled the country and has lived in exile in France ever since.
The second president, Mohammad Ali Rajai, was elected in July 1981 and assassinated by bomb soon after. He was replaced by Ali Khāmenei in October 1981 and re-elected in 1985. In 1989 the Reformist, Akbar Hashemi Rafsanjani was elected and again in 1993. He was replaced for two terms by Mohammad Khatami, who served from 1997 to 2005 and then in 2005 Mahmoud Ahmadinejad was elected. He was re-elected in June 2009 but under controversial circumstances which led to an uprising which was subsequently violently subdued.
Mahmoud Ahmadinejad remained a controversial figure throughout his presidency and the economy declined. His presidency was also known for his hard stance on the development of nuclear power and the subsequent economic sanctions imposed on the country by the West.
On 14th June 2013 Hassan Rouhani was elected as the new president and immediately embarked on a more measured approach. His speech at the United Nations General Assembly in September 2013 was widely acclaimed and his visit to the World Economic Forum at Davos in January 2014 has brought renewed hope of a thaw in relations with the West.
There are several political bodies which are unique to Iran which require explanation.
The Guardian Council is made up of 12 jurists appointed by the Supreme Leader and six jurists by the Majlis or parliament. The council interprets the constitution, has the right to reject legislation from parliament which in incompatible with the constitution or Sharia (Islamic law) and it approves (or otherwise) candidates for national elections.
The Expediency Discernment Council of the System is a body of around 30 people appointed by the Supreme Leader which has the task of resolving disputes between the parliament and the Guardian Council.
The Assembly of Experts is made up of 86 “virtuous and learned” clerics who are elected every eight years. The Assembly has the role of electing the Supreme Leader and also removing him at any time.
The Supreme Leader is appointed for life by the Assembly of Experts. The President is elected by popular vote for a four-year term and is eligible to serve a second term.
The unicameral Islamic Consultative Assembly has 290 members elected by popular vote to serve four year terms.
The Transparency International Corruption Perceptions Index (CPI) 2016 places Iran at joint 131st out of 176 countries with a CPI 2016 score of 29 (where 100 is least corrupt).