Peru was the home of the Inca Empire. The Incas were a well-organized Indian civilization that began the city of Cuzco (now called Cusco). Beginning in the 1400s, they defeated many nearby tribes and built an empire in the Andes. The Inca forced the people to work for the king for a certain number of days every year. They used this "work tax" to build roads and terraces on the sides of the mountains to grow crops, and huge cities with rich palaces for the rulers and their queens. Records were kept on quipa, knotted ropes, since the Incas never invented writing. These could be quickly sent anywhere in the empire by a series of relay runners set up along the roads. Heavier loads were sent by llamas, the pack animals of the Andes.