The south of Laos boasts one of the worlds largest deposits of dinosaur bones. During the 1930s French geologist Josue Heilman Hoffet discovered significant deposits of fossilised bipedal and quadropedal herbivores, freshwater molluscs, crocodiles and tortoises in the region of Ban Tangvai, 120 kilometres east of Savannakhet. No further research was undertaken on this important find until 1990, when a joint Lao-French paleontological team not only rediscovered Hoffets deposits, but also uncovered substantial new dinosaur remains in the area. Further joint field research in 1991 and 1992 revealed the well-preserved remains of sauropods, theropods and ornithopods. Today these important finds may be viewed at the Dinosaur Museum in Savannakhet.
Early in the 20th century homo erectus bones estimated to be between 500,000 and 300,000 years old were found in a cave in Houaphanh Province in north eastern Laos, but after being shipped to France they vanished without trace. More recently, stone implements and skulls were discovered in northern Laos during the Lao-Belgian Mekong River Valley Archaeological Survey of 1998-1999, testifying to the existence of human settlement there from as early as 40000 BCE. However, not until the neolithic period is it possible to shed significant light on Lao prehistory.
The discovery of elaborate burial sites in present-day Houaphanh, Luang Namtha and Xieng Khouang Provinces suggests that by the 1st millennium BCE sophisticated societies were flourishing in those regions.
In Houaphanh Province groups of hilltop standing stones or menhirs dating from around 1000-500 BCE mark the entrances to stone crypts containing human remains, ceramics, beads and bronze artefacts. Hintang Houamuang comprises some 20 menhir sites, the largest and best-known being those of San Kong Phanh. The latter comprises three main clusters, each linked to the other by isolated groups of menhirs. The menhirs themselves take the form of long and narrow blades of roughly-cut schist erected upright in the ground, one behind the other, with the tallest usually in the middle. They were erected over burial chambers excavated deep into the bedrock; access to the opening below was often through a narrow vertical chimney equipped with steps. Each of the burial chambers was covered by a large stone disc measuring up to two metres in diameter.
Believed to date from the same period as the menhirs of Hintang Houamuang, the standing stones of Hintang Nalae in a remote area of Luang Namtha Province are similar in shape but incised with various designs, underscoring their ritual importance.
However, perhaps the best-known ancient necropolis in Laos is the Plain of Jars in Xieng Khouang Province, where thousands of massive stone jars sculpted out of single pieces of stone have been found grouped in clusters across the Xieng Khouang Plateau, 1,000 metres above sea level. Scholars believe that the people who made the jars were the iron-using descendants of the people who created the standing-stone burials in Houaphanh Province; stone and bronze tools are not sturdy enough to carry out this kind of work, but the advent of iron forging in around the 4th century BCE would have offered new creative opportunities to the prehistoric necropolis builders.
To date some 50 jar fields have been identified, usually situated on promontories and other strategically high places; some sites contain more than 250 individual jars. At two of these sites earthenware jars have been found containing human bones. Scholars believe that the dead were first interred in the giant stone urns which were sealed with carved lids; the bodies were later disinterred, cremated and buried in earthenware jars. Both stone and earthenware urns were decorated with motifs such as cats, stars, or the raised-arm figure that the modern Lao call the frog man. Some of the grave-goods found in the jars indicate that the Plain of Jars civilisation engaged in international trade with China, India and neighbouring societies. The Plain of Jars is rich in salt, and it is likely that this commodity – highly valued at the time – secured its place on international trade routes.
In the early 1990s pots and other artefacts dating from the 2nd century BCE to the 3rd century CE were discovered during the construction of a tourist resort on small hill at Lao Pako on the Nam Ngum River near Vientiane. In 1995 a joint archaeological project with Sweden was set up, resulting in excavations in 1995-6 and 2002 and a site survey in 2002. Over 70 complete vessels were unearthed here, including jars, pots, bowls and plates; two of the vessels contained intact burials of young children, indicating the site to be yet another neolithic necropolis. In addition to pottery, excavations have revealed evidence of iron and textile production, which was believed to have been used for ritual purposes. Strong similarities have been noted between the decorative features of the pottery of Ban Pako and that of the pottery found at Ban Chiang and Ban Na Di in North East Thailand.