Jars of Laos, page 1

While surfing the net today I bumped into an interesting article about Jars of Laos
I did some search on ATS, but didn't find more than this which quotes article from Boston Globe.
For those, who don't feel like clicking the links I will quote some parts :

Perhaps 2,000 years old, the relics on the plateau known as the Plain of Jars are one of the oldest -- and unexplained -- archeological wonders of Southeast Asia. They have survived looters, the elements, and American bombs, but for decades were largely forgotten in the chaos and conflict that swept Laos.

Archeologists say there are thousands of jars in this part of northern Laos. Experts believe that the urns were used in burial rituals, but they know little about the people who made them.

and

Most Laotians believe that the urns were made by a sixth-century chieftain, Khun Jeuam, to celebrate his victory in battle over a local tyrant.

Despite the myth's popularity, archeologists say the jars were carved from solid sandstone and limestone centuries before the chieftain's time. The sites, they say, were cemeteries, and the urns once held corpses. No bodies have been found in the urns, but traces of human remains have been discovered inside a few, and skeletons have been unearthed nearby.French archeologist Madeleine Colani first brought the jars to the world's attention in the mid-1930s. She discovered and documented hundreds of them and theorized that they were used in burials. She also reported finding bronze and iron tools, carnelian beads, and a bronze figure, but the relics have since been lost or stolen.

Engelhardt said the jars lie along an ancient road linking the Red River Delta of North Vietnam with southern India. Megaliths that may have been made by the same people have been found along the route as far as Bangladesh.

Here is another article about them:
Laos Keeps Its Urns
Great pictures, but unfortunately it doesn't contain much more information.

Does anybody know more about Jars of Laos? Maybe some interesting teories about their origin?
I welcome any sources

Thanks, jazzgul