Timeline of Iranian history
The Achaemenid Empire (pron.: //; Old Persian: Parsā, name of ruling dynasty: Haxāmanišiya) (c. 550–330 BC), also known as the First Persian Empire, was a Persian empire in Western Asia, founded in the 6th century BC by Cyrus the Great who overthrew the Median confederation. The dynasty draws its name from king Achaemenes, who ruled Persia between 705 BC and 675 BC. The empire expanded to eventually rule over significant portions of the ancient world which at around 500 BC stretched from the Indus Valley in the east, to Thrace and Macedon on the northeastern border of Greece, making it the biggest empire the world had yet seen. The Achaemenid Empire would eventually control Egypt as well. It was ruled by a series of monarchs who unified its disparate tribes and nationalities by constructing a complex network of roads.
Calling themselves the Pars after their original Aryan tribal name Parsa, Persians settled in a land which they named Parsua (Persis in Greek), bounded on the west by the Tigris River and on the south by the Persian Gulf. This became their heartland for the duration of the Achaemenid Empire. It was from this region that eventually Cyrus the Great (Cyrus II of Persia) would advance to defeat the Median, the Lydian, and the Babylonian Empires, opening the way for subsequent conquests into Egypt and Asia Minor.