Machu Picchu ruin 'found earlier'
The site is believed to have been ransacked by a German adventurer in the 1860s.
Machu Picchu, now Peru's biggest tourist attraction, was famously believed to have been discovered in 1911 by US explorer Hiram Bingham.
The ruins are the crown jewel of Peru's archaeological sites in Peru and draw thousands of tourists every day.
Machu Pichu carries symbolic value for Peru's indigenous people.
It was built by one of the last Inca emperors, Pachacutec, in around 1450 and kept secret from the Spanish conquerors who invaded about 100 years later.
Now the story about its discovery by the western world has been shaken up by a team of historians who say a German businessman looted its treasures more than 40 years before.
They say the adventurer, Augusto Berns, who traded in Peru's wood and gold, raided the citadel's tombs in 1867 apparently with the blessing of the Peruvian government.
He had set up a sawmill at the foot of the forested mountain on which Machu Picchu stands and systematically robbed precious artefacts which he sold to European galleries and museums.
Only when one of the historians found a map in Peru's national museum were his activities traced.