The Inca were a powerful civilization that thrived in the Andean region of South America from the early 15th century until the Spanish conquest in the 16th century. They are known for their advanced agricultural techniques, impressive architectural achievements like Machu Picchu, and a vast network of roads that facilitated trade and communication across their empire. At the height of their power, the Inca Empire was the largest empire in pre-Columbian America, encompassing parts of modern-day Peru, Ecuador, Bolivia, and Chile. The Incas had a rich culture, with a complex social structure, religious beliefs centered around the sun god Inti, and a unique system of record-keeping using quipus (knotted strings).