<P> The knowledge of these myths is due to oral tradition, since the Incas did not have writing . Manco Cápac, who became the leader of his tribe, probably did exist, despite lack of solid evidence . The archeological evidence seems to indicate that the Inca were a relatively unimportant tribe until the time of Sinchi Roca, also called Cinchi Roca, who is the first figure in Inca mythology whose existence can be supported historically . </P> <P> The Inca people began as a tribe in the Cusco area around the 12th century AD . Under the leadership of Manco Cápac they formed the small city - state of Cusco Quechua Qosqo . </P> <P> In 1438 AD, under the command of Sapa Inca (paramount leader) Pachacuti, whose name meant "world - shaker", they began a far - reaching expansion . The land Pachacuti conquered was about the size of the Thirteen Colonies of the United States in 1776, and consisted of about half the Andes mountain range . </P> <P> Pachacuti reorganized the kingdom of Cusco into an empire, the Tahuantinsuyu, a federalist system which consisted of a central government with the Inca at its head and four provincial governments with strong leaders: Chinchasuyu (NW), Antisuyu (NE), Kuntisuyu (SW), and Qullasuyu (SE). Pachacuti is also thought to have built Machu Picchu, either as a family home or as a Camp David - like retreat . </P>

Who was the inca king who began the conquest that led to the creation of their empire