The Incas The Incan state, an agriculturally based theocracy, was dominated by the all-powerful, semidivine Inca. Administratively, the entire domain was divided into four great regions or quarters, which in turn were subdivided intoprovinces and various lesser socio-economic units. Farming was under strictofficial control. The state took and stored a portion of each grain harvest, to be doled out as the need arose. Example of Inca architecture in Machu Picchu. The stones appear to be rough, but they fit perfectly together, so tight that not even a knife can fit between them. Until today, it is uncertain what kind of technology the Incas used to get this done. Image © Hector A. Patrucco Inca religion was highly formalised and rituals centred on agricultural and health concerns. The supreme Inca deity was Viracocha, creator and ruler of all living things. Other major deities were the gods of the sun, stars, and weather and the goddesses of the moon, earth, and sea. The Incas were established in the Cuzco valley by 1100 AD. In the middle of the 15th century they began to undertake imperialistic expansion under the eighth ruler, Viracocha Inca. In a period of about 30 years, the Incan domain was enlarged and unified more than athousand times by Viracocha's son, Pachacuti Inca Yupanqui, and Pachacuti'sson, Topa Inca Yupanqui. The empire reached its greatest extent in the reign of Topa's son, Huayna Capac, in the early 1500s. A struggle for the throne followed the death of Huayna Capac in 1525.Two of his sons, the half brothers Huáscar and Atahualpa, fought bitterly until the capture of Huáscar in 1532. When Spanish explorer Francisco Pizarro arrived on the coast with a small armed force that same year, he took advantage of the civil strife; he gained control of the centralised Incan state by taking Atahualpa prisoner and later executing him. Pizarro placed on the throne Manco Capac, a brother of Huáscar, who later led an unsuccessful revolt against the Spaniards. The last Inca to hold thethrone, Tupac Amaru, was executed by the Spaniards. See also: history. El Torreon in the Inca city of Machu Picchu