A lion engraving found in the Persian capital of Persepolis

The Persians, under the rules of Cyrus the Great, Darius I, and Xerxes, created the largest empire known up to that time. Important contributions of the Persian Empire include enacting an imperial bureaucracy and building formal roads for trade and travel. The Persian Empire was very accepting of the people who were conquered as the empire grew and new lands were acquired. At that time, a Persian thinker named Zoroaster created a new monotheistic religion called Zoroastrianism. This religion includes the concept of opposing good and evil forces, and is still practiced today.