Machu Picchu National Geographic again and with the full support of Peruvian President Leguia. The expedition undertook a four-month clearing of the site with local labour, which was expedited with the support of the Prefect of Cuzco. Excavation started in 1912 with further excavation undertaken in 1914 and 1915. Bingham focused on Machu Picchu because of its fine Inca stonework and well-preserved nature, which had lain undisturbed since the site was abandoned. None of Bingham's several hypotheses explaining the site held up. During his studies, he carried various artifacts back to Yale. One prominent artifact was a set of 15th-century, ceremonial Incan
Machu Picchu push the stones up inclines. A few stones have knobs that could have been used to lever them into position; the knobs were generally sanded away, with a few overlooked. The Inca road system included a route to the Machu Picchu region. The people of Machu Picchu were connected to long-distance trade, as shown by non-local artifacts found at the site. For example, Bingham found unmodified obsidian nodules at the entrance gateway. In the 1970s, Burger and Asaro determined that these obsidian samples were from the "Titicaca" or Chivay obsidian source, and that the samples from Machu Picchu showed long-distance