The Kingdom of Cusco: the Inca state before the empire

The Incas had no writing, and the history of the Kingdom of Cusco is known from traditions recorded by Spanish chroniclers in the 16th century. They name eight rulers before Pachacuti: the Hurin Cusco ("lower Cusco") dynasty of Manco Capac, Sinchi Roca, Lloque Yupanqui, Mayta Capac and Capac Yupanqui, followed by the Hanan Cusco ("upper Cusco") rulers Inca Roca, Yahuar Huacac and Viracocha Inca. The early rulers probably bore the titles kuraka or sinchi (war leader) until Inca Roca introduced the title Sapa Inca. Their dates are unknown: the dynasty is conventionally dated from about 1200, and some scholars regard much of this early history as mythical. Before the Incas the Cusco Valley was home to the Killke culture (about 900–1200), whose builders, according to one archaeologist, raised the earliest parts of Sacsayhuamán in the 12th century.

The chronicles describe how the rulers of Cusco fought and allied with their neighbours — the Alcahuisa, Saños, Huallas and other peoples of the valley, and the powerful Ayarmaca, with whom Sinchi Roca and Lloque Yupanqui waged war — sealing alliances by marriage; Mayta Capac consolidated Cusco's power in the valley, and Viracocha Inca conquered the valleys of Yucay and Calca on the Urubamba. The origins of the Incas are debated. One version of their legend brings Manco Capac from Lake Titicaca, and the linguist Rodolfo Cerrón-Palomino argued that the secret language of the Inca nobility was related to Puquina, a language associated with Tiwanaku; Alfredo Torero rejected this "Puquinist hypothesis".

In the early 15th century the expanding Chanka threatened Cusco. According to Inca tradition, Viracocha Inca and his co-ruler Urco fled, while his son Cusi Yupanqui defended the city, defeated the Chanka and took power as Pachacuti, turning the Kingdom of Cusco into Tawantinsuyu, the Inca Empire. John H. Rowe, following the chronicler Miguel Cabello de Balboa, dated the beginning of this reign to 1438; the date is conventional, and radiocarbon dates suggest that it came earlier, at the beginning of the 15th century.