The empire known for its vast territory and significant contributions to law and governance during its peak around the 5th century BC was the Achaemenid Empire, also known as the Persian Empire. Founded by Cyrus the Great, it became the largest empire in history at the time, encompassing regions across three continents. The Achaemenid Empire is notable for its sophisticated administrative practices, including the establishment of satrapies and the use of written laws, such as the Royal Road for communication and trade. Its cultural and legislative achievements laid the groundwork for future governance in many subsequent civilizations.