Iran's history stretches back thousands of years. The country lies at the heart of the ancient Persian Empire established by Cyrus the Great and Darius the Great in the 6th and early 5th centuries BCE.
The Persian Empire is conquered by Alexander the Great towards the end of the 4th Century BCE, beginning a period of Greek influence on Iranian culture that extends well beyond Alexander's death in 323 BCE.
The Persian Empire and its associated Iranian cultural traditions reemerge at the start of the 3rd Century CE. The restored empire lasts for 400 years until it is conquered by Islamic invaders from Arabia in the middle of the 7th Century. Over time, the majority of Iranians convert to Islam, adopting the Shia branch of the faith. (Shia Islam becomes the state religion of Iran in the 16th Century.)
At the start of the 13th Century, Iran comes under the control of a new wave of invaders - Mongol tribes led by Genghis Khan. The Mongols remain in power until 1502, when Iranians seize back their homeland and establish a Shia theocracy led by a shah (king).
From the beginning of the 19th Century, Iran is subjected to interference and land grabs by Britain and Russia. Towards the end of the same century, popular discontent with the growing foreign influence and the inefficiencies and corruption of the royal regime mounts and becomes increasingly vocal. In August 1906 the shah is forced to issue a decree promising the introduction of a new constitution.
The constitution that is subsequently drafted places strict limitations on royal power and establishes a representative parliament, or Majlis. The shah signs the new constitution on 30 December 1906. He dies five days later.
In 1908 oil is discovered in Iran.