Cyrus the Great was the famed ruler of the Achaemenid Empire during its peak, which flourished in the 6th century BC. He founded the empire by uniting the Medes and Persians, and his conquests extended from the Aegean Sea to the Indus River, making it one of the largest empires in history. Cyrus is renowned for his progressive approach to governance, including the respect for local customs and religions, which fostered stability. His legacy is encapsulated in the Cyrus Cylinder, often regarded as one of the earliest declarations of human rights, laying the groundwork for a multi-ethnic empire.