The Inca or Incaico Empire was the largest empire in pre-Columbian America and encompassed about three million square kilometers, from the Pacific Ocean to the west to the Amazon rainforest in the east, and from the Ancasmayo River to the north to the Maule River to the south and Tucumán to the south east. Inca empire. Pre-Inca cultures. Machu Picchu. Cuzco