The civilization that built the largest empire in the ancient world was the Persian Empire, particularly under the Achaemenid dynasty. At its height in the 5th century BC, it extended over three continents, including parts of Asia, Africa, and Europe. The Persian Empire was known for its impressive administration, religion, and infrastructure, including the Royal Road facilitating communication and trade. Leaders like Cyrus the Great and Darius I contributed to its expansion and cultural achievements by promoting tolerance among the various peoples within the empire. Its influence is evident in subsequent empires, and it greatly shaped historical developments in the region.