Khai quật công xưởng chế tác vòng tay đá thời tiền sử Đồi Phòng Không (Đồng Nai) năm 2019

The artifacts belonging to the manufacturing process of stone bangles: (1) Shaping the preforms. The first stage of transformation may be done at the quarrying sites where the stone is reduced to achieve a bifacial disc. This shaping allows the reduction of the quantity of raw material for later transportation to the workshops. (2) Drilling out a core. Products of the manufacturing process including the disc with drill marks from one side, core rings, and bracelets broken before polishing were found. Both techniques with polished drill bit and rotating-grinding tools have been reported. (3) Grinding and finishing the product. When the disc bracelets were completed, internal edges were polished with sandstone tools. The cylindrical tool permits the finishing of the internal edge, whereas the grooved polishing stones were used to smooth the surface and outer edges of the bracelets. The finished products are dispersed from this site, so they can be done in another location.
The chronological of Đồi Phòng Không is in the range of 2700 - 2500 BP. The Đồi Phòng Không archaeological site was discovered in 1985 and is a specialized stone bracelet workshop. The core relic area located on the hilltop area, about 4,000 square meters wide. The excavation results in 2019 show that artifacts are concentrated mainly on the southwest hillside. Four excavation pits, with a total area of 40m², have been opened in this area, showing that the cultural layer is about 30 - 40cm thick.
The relic has a close relationship with Bưng Bạc and other prehistoric sites in Đồng Nai culture. The stone bracelets, given their intricate technology, are linked with the early stages of craft specialization, the beginnings of social organization, and the circulation networks of goods.