21 May 2006 () – Vietnamese archaeologists find more evidence of a pre-Dong Son culture.
Archaeologists believe that excavations of Den Citadel, said to date back more than 3,000 years, will provide evidence to support their theory about the evolution of the Van Lang kingdom.
Archaeologists have found bronze arrows, javelins, needles, earings, fishing hooks, and axes from the Dong Dau era as well as an ancient bronze kiln that was made of sandstone and terracotta with many tools. Artifacts found after four excavations have led archaeologists to the conclusion that the Den Citadel was a bronze tools production factory in the continental Southeast Asia. At this site, the number of relics found on 1sq.m is higher than in any other pre-historic excavation site in Viet Nam.
The Archaeology of Mainland Southeast Asia: From 10,000 B.C. to the Fall of Angkor by C. Higham
Southeast Asia: From Prehistory to History by I. Glover
The Bronze Age of Southeast Asia (Cambridge World Archaeology) by C. Higham