The Plain of Jars in Laos is a mysterious terrain with massive stone jars of unknown ancient origins. Shrouded in mystery is not just these jars, but also the civilization that created them.

Now, Australian archeologists have uncovered what they now believe as burial grounds at one of the most captivating and mysterious sites in Asia.

The team from the Australian National University found human remains estimated to be 2,500 years old in one of the jars, which range from 3 to 10 feet tall and weighing more than 10 tons.

These are the first major archeological finds since the 1930s at the Plain of Jars and the 90 sites forming it – potentially taking scientists a step closer to understanding the purpose and origins of the carved stone jars in the area.

“One theory is that [the jars] were used to decompose the bodies. Later, after the flesh was removed the remains may have been buried around the jars,” says Dougald O’Reilly, who led the team.

It is now apparent, says O’Reilly, that the jars – numbering from one to 400 at every site – served as a mortuary and functioned specially for disposing of the dead.

Their archeological discovery from the excavations last February showed three different kinds of burial: pits filled with bones covered by a large limestone block, burials with bones placed in ceramic vessels, and a primary burial that houses a grave.

It could get difficult to determine the status and identity of the buried humans because there were very few material things buried with their bodies. Some are found with the remains were only a few simple items, including a handful of glass beads. On the other hand, the ancient sites these bodies were located are believed to date from 500 or 600 BC to 550 AD.

At present, archeologists hope that genetic analysis could help them know who the individuals were related to, as well as their general behavior in the community. A joint Australia-Laos team is currently researching and collecting data at the site.

The government of Laos is pursuing a UNESCO World heritage site standing for the Plain of Jars, which would come with benefits related to preservation, worldwide recognition, and tourism.