Mexico’s mass grave is a 1300-year-old cemetery (VIDEO)

Mexican anthropologists said the remains of 167 bodies found in a cave in the southern state of Chiapas were part of an ancient pre-Hispanic burial ground, according to BBC News. The National Anthropology Institute said tests showed the remains dated back to the 8th century.

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Authorities found the skeletal remains on Friday on the Nuevo Ojo de Agua ranch in a region where Central American migrants pass while heading north, reported The Huffington Post. Local farmers were the first to come across the cave last week and they alerted authorities of their findings.

Initial tests suggested the bodies, which were found only 20km (11 miles) from the Guatemalan border, were at least 50 years old, making some activists in Guatemala speculate they may have belonged to victims of the country's 1960 to 1996 civil war, according to BBC News.

But forensic experts now say the skulls show signs of a deformation typical of native communities that date back at least 1000 year, reported the Daily Mail. The Maya people, who lived in southern Mexico and neighboring Guatemala for nearly 2000 years, used planks to flatten and elongate the skulls of their children when they were infants.

BBC News reported that anthropologists are still examining the remains to determine the sex, age and ethnic makeup of the bodies.