The find is believed to be the first in the region showing the practice of binding a skull to change its shape.
'Cranial deformation in Mesoamerican cultures was used to differentiate one social group from another and for ritual purposes,' said archaeologist Cristina Garcia Moreno, director of the research project.
The burial ground consists of 25 individuals; 13 have intentional cranial deformation and five also have dental mutilation.
Garcia Moreno the conductor of the dig, working behalf of Arizona State University said:
"This unique find shows a mix of traditions from different groups of northern Mexico,' said Moreno.
The dental mutilation in cultures such as the Nayarit was seen as a rite of passage into adolescence,' said Moreno.
This is confirmed by the findings at the Sonora cemetery where the five bodies with dental mutilation are all over 12 years in age."
"In this case, you cannot recognise any social differences because all the burials seem to have the same characteristics.
Nor have we been able to determine why some were wearing ornaments and others not, or why of the 25 skeletons only one was female."
The team say the number of infants and pre-pubescents could show the high risks involved in the cranial deformation, which can kill from the excessive force squeezing the skull.
The find has been dated to the year 943 CE from samples taken from one of the individuals.
Are these just normal people or a conspiracy theory ?