The Achaemenid Empire, also known as the First Persian Empire, was founded by Cyrus the Great in the 6th century BC. It was a vast empire that stretched from the Balkans and Eastern Europe in the west to the Indus Valley in the east. The empire was known for its efficient bureaucracy, tolerance of different cultures, and impressive infrastructure projects, such as the Royal Road and the city of Persepolis.

Some of the most notable rulers of the Achaemenid Empire were Cyrus the Great, Darius I, and Xerxes I. Cyrus was a great conqueror and a benevolent ruler who allowed conquered people to retain their own customs and religions. Darius I was a great administrator who expanded the empire and improved its infrastructure. Xerxes I is perhaps best known for his invasion of Greece, which ultimately failed.

The Achaemenid Empire was eventually conquered by Alexander the Great in the 4th century BC. However, its legacy lived on through the spread of Persian culture and the influence it had on later empires, such as the Parthian and Sassanian Empires.