The Achaemenid Empire was established by Cyrus the Great in the 6th century BCE. As the founder of this expansive empire, Cyrus united various tribes and conquered significant territories, including the Medes, Lydians, and Babylonians, thus creating one of the largest empires in history. Known for his progressive policies, Cyrus is celebrated for respecting the customs and religions of the lands he conquered, exemplified by his decree allowing exiled peoples, such as the Jews, to return to their homelands. His administration laid the foundations for future Persian empires and influenced governance throughout subsequent history.