In the mid-15th century, the Incas sent their army south from their home in the Cuzco Valley, high in the Andes Mountains, on a stunningly successful campaign of conquest. These early campaigns were led by Pachacuti, the ninth Incan leader and the man described in some accounts as a visionary who created the social, political, and ceremonial order of Incan society.
During Pachacuti's reign, the Incas' powerful realm arose, called Tahuantinsuyu or the "Land of the Four Quarters." It eventually covered an estimated 2,400 miles from north to south, from the current border of Ecuador and Colombia to just south of modern Santiago, Chile. Approximately 10 to 12 million people lived within this 300,000 square mile empire, the greatest on earth at the time.
Considering the esteem in which he was held in early chronicles of Incan history, it is not surprising that Pachacuti's rise to power has the legendary beginnings befitting a great hero. Although details differ in various accounts, some scholars believe that around 1438, a nation known as the Chancas invaded the Cuzco Valley. Rather than face certain defeat, Pachacuti's brother Urco and their father, Incan leader Viracocha, left Cuzco for a mountain hideout. Remaining behind, Pachacuti assembled an army and led it into battle against the Chancas. His forces fought valiantly but were outmatched and in danger of defeat when nearby rocks turned into soldiers who slayed the Chancas and their chief, Uscovilca. After the battle, the warriors turned back into stone, but the legend of the great Incan battle, and Pachacuti's success, lived on.
Despite Pachacuti's victory, Viracocha was determined that his son Urco succeed him as Incan leader and schemed to have Pachacuti killed. The attempt failed but when Pachacuti learned that Urco planned to usurp his growing power among the people of Cuzco, he had his brother killed. Viracocha eventually returned to Cuzco and, seeing the improvements in the great city and his son's popularity with the people, he abdicated his throne in favor of Pachacuti. As the Sapa Inca (king), Pachacuti was considered the son of Inti, the Sun God, and ruled by divine right.
When Pachacuti was coronated in 1438, the Incas' entire kingdom consisted of the valley surrounding Cuzco, but within a few years, he began their great expansion. In the first years of his reign, he sent his forces south past Lake Titicaca into what is now Bolivia, then east to the Pacific Ocean and north into central Ecuador. For Incan warriors, incentives for fighting were many. Conquest could result in material and symbolic rewards, including lands, laborers, military honors, offices, and the promise of transforming into important ancestral spirits. Furthermore, Incan rulers waged propaganda campaigns to remind their subjects that the Sapa Inca was divine and that the well being of all rested on his welfare.
In just a few decades, the Incas conquered huge territories and brought numerous peoples into their empire. In many cases, diplomacy may have been as much a factor as military tactics. The mere perception of Incan might led some people to capitulate rather than face defeat, particularly since the Incas were known to be generous to those who surrendered without resisting. And in the many regions plagued by local conflicts, there were no major groups strong enough to defeat the Incas or friendly nations with which they could ally against the Incas.
At some point, Pachacuti is said to have turned over command of the armies to his brothers and son, Thupa Yupanqui, and focused on governance. Historians credit him with devising the plan for Cuzco and starting its transformation from a small town of thatched roof palaces to a grand, planned city with temples, plazas, canals, baths, estates, store houses, and a landscape extensively engineered through terraces to adapt to the rugged terrain and elevation. At its peak, Cuzco and its surrounding area may have housed up to 150,000 people. Some historians now believe that Pachacuti also ordered the building of Machu Picchu, a lavish estate or spiritual retreat high in the mountains and one of the best surviving examples of Incan engineering and architectural prowess.
Under Pachacuti's leadership, the Incas created a vast state, which had direct impact on the lives of the people they ruled. Each person was required to provide two to three months of labor every year to the state, and as the Incas assimilated groups into their empire, they resettled millions of people in productive agricultural areas or military hotspots to work. Up to a third of the population was moved from their traditional homelands. By breaking up local communities, the Incas not only had a source of labor, they also had a way to reduce the potential for uprisings.
To maintain their growing empire, the Incas built on an existing system and created a network of approximately 25,000 miles of roads that connected an estimated 2,000 provincial way stations or administrative and production centers. The road system converged in Cuzco, the political and spiritual center of the Tahuantinsuyu. In his mid-16th-century account of Incan history, Spanish chronicler Juan de Betanzo credits Pachacuti with creating the Incas' vast storage system. It eventually numbered tens of thousands of storehouses throughout their empire, supplying their administrative leaders, military and religious personnel, and state laborers with food, clothing, and raw materials. Food and supplies were also available to help the general population in times of drought or flood.
In 1471, Pachacuti gave up his throne to his hand picked successor, his son Thupa Yupanqui, who would continue his father's conquest campaigns and take the Incan empire to new heights.