They were sacred groups, that is to say, the tombs were sacred places, carefully worked underneath rocks, that protected them from the inclemency of the environment.
There are 04 peripheral cemeteries, plus a funerary cave in the cave of the serpent and in the sacred square.
The most extensive study of this field was conducted by George F. Eaton who made the most complete collection of tombs in Machu Picchu, as part of the 1912 expedition sponsored by Yale University and the National Geographic of the United States.