The skeletons were found ritually “intertwined” and examinations showed all their heads had been damaged and teeth mutilated.
They were buried along with bowls, pots and basins. Some also had ceramics and stones in their hands.
Lead anthropologist Lucia Lopez Mejia said the bodies were laid out in a spiral shape and were “interacting”.
They were placed directly on the earth with their bodies were linked so the arm bones of one individual appear under the spine of another.
Archaeologists said they would have been among the earliest settlers near what is now Mexico City.
Eight of them are believed to be young adults and one is a child between three and five years of age. Another is a baby believed to be just a few months old.
The amazing discovery was made in Tlalpan, south of Mexico City, by experts from the National Institute of Anthropology and History (INAH) on the grounds of the Royal and Pontifical University of Mexico.
The skeletons were found 4.9ft below what used to be the University’s oratory and is the first grave containing a large group of people to be found in the area.
The site dates back to the Preclassic period of Mayan history and falls between the Middle (1000-400 BC) and Late (400 BC-250 AD) periods.
Although little is known of civilisations living in the area at this time, Dr Rivera Escamilla hopes to shed more light on them.
She believes that the area was settled for over 500 years during the end of the Middle and at the beginning of the Late periods.
The Mayans were terrified of death and believed people died because their souls had been stolen by evil spirits.
Scientists said the discovery may help shed more light on the Mayan civilisation and their mysterious death rituals.
Experts are hoping the graves, which have not yet been fully investigated, may also include ornaments or other tributes for the dead in the afterlife.