Pachacuti was the ninth ruler of the Inca Empire, reigning from 1438 to 1471. He is often credited with transforming the Inca state from a small kingdom into a powerful empire. Under his leadership, the Incas expanded their territory significantly, conquering neighboring regions and establishing a centralized government. Pachacuti is also known for his ambitious building projects, including the famous city of Machu Picchu. He implemented administrative reforms and promoted the worship of the sun god, Inti, which helped unify the diverse cultures within the empire. His legacy laid the foundation for the Inca civilization's future successes.