The greatest period of Inca expansion occurred during the reigns of Pachacuti (1438-71), Tupa Inca (1471-93), and Huayna Capac (1493-1527). From the mountain stronghold of Cuzco, they subjugated the surrounding kingdoms and territories, absorbing their civilizations and their peoples. By 1525, they dominated much of the west of the continent, relying on fortified strongholds, an extensive system of roads an bridges, and obligatory military service...