The fortress of Machu Picchu was occupied during different periods. Judging from the crónicas (early written history), the building style and the ceramic articles found, the following Periods have been calculated:Early: 1300 ad
Classical: 1400 ad
Imperial: 1533 ad
Transition: 1533-1572 ad

The history of Machu Picchu

Most modern archaeologists and historians coincide that Machu Picchu was built by the Inca Pachacutec, the greatest statesman in Tahuantinsuyo, who governed from 1438 to 1471. Archaeologists infer that the citadel’s construction dates from the fifteenth century approximately, a date confirmed by carbon 14 (radioactive carbon) dating. Machu Picchu’s construction coincides with the start of the expansion of the small feudal kingdom of the Incas. According to archaeologists, the final battle defining the Incas’ victory over the Chancas, a prestigious victory that gave much power to Inca Pachacutec, was fought in this area.Pachacutec was the first Inca to expand beyond the valley of Cusco after his epic victory over the Chancas. He was the author of Tahuantinsuyo’s expansion and is recognized as the “constructor” of Cusco. This was one of his greatest works. Machu Picchu’s origin is attributed, with a certain degree of authority to Pachacutec, a warlike leader, noted for both territorial conquests and the development of religion and spirituality. This is why present archaeological researchers tend to support the theory that it was a royal hacienda destined for the worship of the Inca’s gods, as well as a mighty challenge to the monarch’s construction skills.Built as a refuge for the elite of Inca aristocracy, the fortress was located on the eastern slope of the Vilcanota Cordillera, some 80 km from Cusco, the capital of the empire. Its strategic geographic location was amazingly well chosen. Surrounded by steep cliffs and secluded from the sight of strangers by the thick jungle around it, the citadel of Machu Picchu had the special virtue of possessing only one narrow entry point, which enabled a successful defense by a handful of warriors in the event of surprise attack.Occupied by at least three generations of Incas, the fortress of Machu Picchu was abandoned in a sudden and mysterious way. The most likely theories explain its disappearance from historical memory by the fact that its existence was unknown to the lower castes, and all but the small circle of the Inca’s immediate retinue were forbidden to approach it.Pachacutec’s conquests included the valley of Tampu, that was inhabited by a sister tribe to the Cusco, but one that did not escape its all-encompassing rule. Due to its natural beauty and mild climate (one of the best in the Andes), as well as its fertile soil, Tampu was chosen by Pachacutec as the seat of the new imperial nobility, and the valley was embellished with several of Tahuantinsuyo’s most attractive cities, such as Ollantaytambo and Machu Picchu. The choice of Machu Picchu’s site must have been made with great care, because it was, and still is, the ideal place to locate a center for worship. According to researcher Antonio Zapata, it is located in a mountain chain of sacred significance, starting at Salcantay (the apu, or great spirit) and ending in Huayna Picchu. It was a privileged spot to view the heavens and the movements of sun and stars, which were the deities of the Incas. Moreover, according to his research, there was a nearby quarry supplying white granite of very fine quality.