Pachacuti Inca Yupanqui (or Pachacutec) was the ninth Sapa Inca (1438-1471/1472) of the Kingdom of Cusco, which he transformed into the empire Tawantinsuyu. In Quechua, Pachakutiq means "He who remakes the world". During his reign, Cuzco grew from a hamlet into an empire that could compete with, and eventually overtake, the Chimu. He began an era of conquest that, within three generations, expanded the Inca dominion from the valley of Cuzco to nearly the whole of civilized South America.
Pachacuti also reorganized the new empire, the Tahuantinsuyu or "the united four provinces." Under his system, there were four apos that each controlled one of four provinces (suyu). Below these governors were t'oqrikoq, or local leaders, who ran a city, valley, or mine. By the time of the Spanish conquest of Peru, each apo had around 15 t'oqrikoq below him, but we can assume there were fewer when Pachacuti first organized this system. He also established a separate chain of command for the army and priesthood to establish a system of checks and balances on power.
Pachacuti rebuilt much of Cuzco, designing it to serve the needs of an imperial city, and indeed as a representation of the empire. There was a sector of the city for each suyu, centering on the road leading to that province; nobles and immigrants lived in the sector corresponding to their origin. Each sector was further divided into areas for the hanan (upper) and hurin (lower) moieties. The Inca and his family lived in the center; the more prestigious area. Many of the most renowned monuments around Cuzco, such as the great sun temple of Coricancha or the "fortress" of Sacsayhuamán, were constructed during Pachacuti's reign.
Despite Pachacuti's political and military talents, he did not improve upon the system of choosing the next Inca. His son became the next Inca without any known dispute after Pachacuti died in 1471 due to a terminal illness, but in future generations the next Inca had to gain control of the empire by winning enough support from the apos, priesthood, and military to either win a civil war or intimidate anyone else from trying to wrest control of the empire. Pachacuti is also credited with having displaced hundreds of thousands in massive programs of relocation and resettling to occupy the remotest corners of his empire. These forced colonists where called mitimaes and represented the lowest place in the Incan social ladder. In a way the Incan imperial government was highly despotic and repressive.
Machu Picchu is believed to date to the time of Pachacuti.
Pachacuti was a poet and author of the Sacred Hymns of the Situa city purification ceremony.