The Kingdom of Iran (پادشاهی ایران) is a constitutional monarchy in the crossroads of Central Asia in the Middle East. It borders Armenia, Azerbaijan, the Ottoman Empire, Afghanistan, India, and Khiva.
During the second millennium BCE, Proto-Iranian tribes arrived from the Eurasian steppes, rivaling the native settlers of the country. These tribes dispersed into the area of Greater Iran, beyond the boundaries of Modern Iran that were dominated by Persian, Median, and Parthian tribes. From the late 10th to late 7th centuries BCE, the Iranian peoples, together with the "pre-Iranian kingdoms," fell under the domination of Assyria. In 728 BCE, the unification of Median tribes led to the foundation of the Median Empire in 612 BCE, which ruled the whole of Iran and eastern Anatolia. In 550 BCE, Cyrus the Great took over the Median Empire, founding the Achaemenid Empire in an event called the Persian Revolution. Cyrus and his successors expanded he empire to include Lydia, Babylon, parts of the Balkans, and eastern Europe. At its greatest extent, the Achaemenid Empire included the territories of modern-day Iran, Azerbaijan, Armenia, Georgia, Anatolia, and much of the Black Sea region. According to Guinness World Records, the empire at its peak ruled over 44% of the world's population, the highest such figure for any empire in history. In 334 BCE, Alexander the Great invaded the Achaemenid Empire, defeating the last emperor and taking control of the empire. In the middle of the 2nd century BC, the Parthian Empire rose to become the main power in Iran, beginning the long rivalry between the Romans and the Persians. They were the two dominant world powers at that point. The Sassanids eventually took over, creating the Sassanid Empire. It is generally considered one of the most influential periods in Iranian history, influencing the culture of ancient Rome, Africa, China, and India. The Sassanid Empire fell after being defeated by invading Muslim Arabs.
Iran came under the rule of the Arab caliphates of Umayyad and Abbasid after being defeated by the Rashidun. The prolonged and gradual process of the Islamization of Iran began following the conquest. Under Arab rule, Persians, both converted and non-converted, where discriminated against, being excluded from the government and being forced to pay a special tax called Jizya. After around two centuries of Arab rule, semi-independent kingdoms started to appear such as the Tahirids, Saffarids, Samanids, and Buyids on the edges of the declining Caliphate. By the 9th and 10th centuries, the efforts of Persians to regain independence had been solidified. The blossoming literature, philosophy, medicine, and art of Iran became major elements in the formation of a new Iranian civilization. During the 10th and 11th centuries Iran was the main theatre of scientific activity. Persian also became the main language of the Islamic world along with Arabic. The 10th century saw a mass migration of Turkish tribes from Central Asia into the Iranian plateau. Turkic tribesmen were first used in the Abbasid army as slave warriors, though they ended obtaining political power, leading to the rise of the Turkish Seljuk and Khwarezmian empires. In 1219–21 the Khwarezmian Empire suffered a devastating invasion by the Mongol Empire. Iran's population did not again reach its pre-Mongol levels until the mid-20th century.
Early modern period
By the 1500s, Ismail I from Ardabil, established the Safavid Dynasty, with Tabriz as the capital. The Iranian identify was changed within the boundaries of Greater Iran. The nation was mostly Sunni, though Ismail instigated a force conversion to Shia Islam. As a result, the only official Shia nations in the world are Iran and Azerbaijan. The centuries-long geopolitical and ideological rivalry between Safavid Iran and the neighboring Ottoman Empire led to numerous wars between the two states. Under Abbas the Great, Persia surpassed their Ottoman rivals in strength. With foreign interference, the Safavid rule was ended by Pashtun rebels who besieged Isfahan and defeated Soltan Hosein in 1722. In 1729, Nader Shah, a military genius from Khorasan, successfully drove out and conquered the Pashtun invaders. He subsequently took back annexed Caucasian territories which were divided between the Ottoman Empire and Russia. Under Nader, Iran reached its greatest extent since the Sassanid Empire, re-establishing the Iranian dominance over the Caucasus, as well as other major parts of western and central Asia. After Nader's reign, Iran fell into chaos and was divided between numerous different kingdoms. The Qajar was the most powerful of these, and eventually dominated most of Iran.
During the 1800s, Russia and Iran fought numerous wars, cementing Russian dominance over the Caucasus. As a result of the 19th century Russo-Persian wars, the Russians took over the Caucasus, and Iran lost control over its integral territories in the region, including Dagestan and modern-day Azerbaijan. About 1.5 million people around 20 to 25% of Iran's population died as a result of the Great Famine of 1870-1871. Between 1872 and 1905, a series of protests took place in response to the sale of concessions to foreigners by Nasser od Din and Mozaffar od Din shahs of Qajar, and led to the Iranian Constitutional Revolution, leading to the formation of Iran's first national parliament as well as their first constitution. The constitution included official recognition of Iran's Christian, Zoroastrian, and Jewish minorities, which still applies to this day. In 1921, the Qajar Dynasty was overthrown, and the modern-day Pahlavi Dynasty was established by Reza Khan, who became the new Shah. In 1941, Reza Shah was forced to abdicate in favor of his son, Mohammad Reza Pahlavi. Modern-day Iran is the second-richest nation in the entire middle east, not far behind the Ottoman Empire.