Archaeologists have discovered tools, ceramics and other objects that indicate evidence of a mysterious society who lived on Vietnam's islands thousands of years ago.

The discovery was made by the Vietnam Maritime Archaeology Project (VMAP) on Quan Lan Island in the Ha Long Bay region.

Bob Sheppard with an ancient bronze weight found at nearby Cai Lang village. ( Supplied: Vietnam Maritime Archaeology Project )

The project was managed by Western Australian archaeologist, author and historian Bob Sheppard, who said the discovery was made by chance after one of his team members had a flat tyre in 2016.

"One of the guys walked along the road cutting and discovered some very old pieces of ceramic," Mr Sheppard said.

"These ceramics — as they turned out — are around 3,000 years old."

The team went back two years later after receiving permission from the local Vietnamese government to excavate the site.

"We did excavations this year at that site and we've come up with material from the ancient people who lived on the islands in Vietnam 3,000 years ago," Mr Sheppard said.

Traditional burial practices led to the find

In Vietnam, when someone dies their body is buried for four or five years. After this time it is dug up and the bones are placed in a pot inside a crypt.

Mr Sheppard said the knowledge of this method of secondary burials as well as the unearthing of a recently-exhumed grave led to further discoveries.



"When they [Vietnamese locals] dig the bones up they leave the grave open," Mr Sheppard said.

"The archaeologists were walking through the grave yard and found this open grave.

"There, in the spoil mound from the grave, was all this Neolithic ceramics and a beautiful polished stone axe," he said.

Ceramics, tools and materials were found about half a metre beneath the surface. This coin was found at a more recent site nearby. ( Supplied: Vietnam Maritime Archaeology Project )

Archaeological mystery

Mr Sheppard said the discovery had created a series of unanswered questions about an ancient, unknown society.

"I think the biggest mystery is what happened to them," he said.

"There is no evidence in the stratigraphy [rock layers] in the archaeology above this level.

"It seems to be some cultural or natural event happened that destroyed this culture around 3,000 years ago

The team will return next year and hope to find an expert on South-East Asian archaeology to help them find out more about the mysterious, ancient culture.

The Vietnam Maritime Archaeology Project says the local provincial government's wish to is protect potential heritage sites. ( Supplied: Vietnam Maritime Archaeology Project )

Cultural significance

VMAP hold a seminar in Ha Long Bay every year to liaise with local heritage officers from provinces across Vietnam.

The seminar also involves looking at how historic sites can be protected.

Mr Sheppard said important heritage sites have been destroyed and lost.

"There is one site we've been looking at which is one thousand years old. It is an old well site," he said.

"We had been surveying it for three years and when we arrived this year somebody had put a bulldozer right through the site and completely destroyed it.

"We are trying to find ways to make sure these sites are protected and the local provincial government really seems to be on our side with trying to work through that."