Iran is heir to one of the world’s oldest civilizations , Some of the world’s earliest urban civilizations flourished in regions that are part of present-day Iran. Of these, the Elamite civilization dates back to before the emergence of written records around 3000 BC. The Elamite city of Susa (which later served as its capital) was founded around 4000 BC in the watershed of Karoun river in southwestern Iran. Through the Elamites, achievements of the Mesopotamian civilizations were introduced to the Iranian plateau. In 646 BC, the Assyrian king, Ashurbanipal, ended Elamite supremacy in the region, and the rise of the Achaemenids a century later formed a nucleus that later expanded into the Persian Empire.
In 6th century BC, Cyrus the Great, regarded as the father of the Iranian nation, united the two major Iranian tribes (the Medes and the Persians) to establish a government centered in Pasargadae (situated in the Fars province of modern-day Iran) that later became the largest, and arguably most prosperous, empire in ancient history, the Achaemenid Empire (c. 550–330 BC). The Achaemenid Empire reached the height of its power during the reign of Darius the Great, who built the new capital city of Persepolis that was described by Greek historians as the richest city under the sun. At its peak, the Achaemenid Empire encompassed an area the size of the contiguous United States that spanned three continents, and was home to an estimated 44% of the world’s population at the time. The rule of the Achaemenid dynasty ended in 330 BC when Alexander the Great captured and destroyed Persepolis. After the fall of the Achaemenid Empire, the Asian territories of the Persian Empire were governed by Seleucid kings until the Parhians emerged as rulers of the Persian Empire. The Parthian Empire (248 BC-224 AD) was the most enduring of the empires in ancient history, even though it was at war with the Roman Empire for almost three centuries. The end of this loosely organized empire eventually came at the hands of Persians of the Sassanid dynasty.
The Sassanid Empire (224-651 AD) ruled a territory roughly within the frontiers achieved by the Achaemenids, with Ctesiphon (in modern-day Iraq) as their capital. In many ways, the Sassanid period witnessed the highest achievements of ancient Persian civilization, and is considered to be one of the most important and influential historical periods in Iran, with a major cultural impact on the rest of the world. The collapse of the Sassanid Empire followed the Arab invasion in the seventh century, during which many Iranian cities were ruined and most Sassanid records and literary works were destroyed.
Safavid Shah Ismail In the thirteen centuries following the Arab invasion, many dynasties have ruled over different parts of the territory comprising modern-day Iran, with different influences on Persian culture and life style. Some of the more enduring dynasties include the Samanids (819–999), the Ghaznavids (975 – 1187), the Seljuqs (11th -13th centuries), the Safavids (1501-1722), and the Qajars (1785- 1925). Among these, the Safavid dynasty was the most significant partly because it followed the Mongol and Turkic invasions in which the conquerors (Genghis Khan, Hulagu Khan, and Tamerlane) destroyed most of Iran’s important cities and undid much of the progress made in the past. In addition, the Safavid dynasty became the first native dynasty since the Sassanid Empire to establish a unified Iranian state.