Our observations on the distribution of minerary/smelting sites around the KSO inselberg were refined and enlarged in 2009 by a systematic, intensive and controlled survey conducted by Thomas Oliver Pryce and his team.
Overall, data collected in the KSO area in 1989-90 indicated a close correlation with what the “Thailand Archaeometallurgy Project” (TAP) was uncovering in the large prehistoric copper mining and smelting sites in the Khao Wong Phrachan Valley, few kilometres north of KSO. The hypothesis of an emergence of bronze metallurgy as a regional phenomenon in the Lopburi river valley, starting from the end of the second millennium BC, deserved to be tested in the KSO area.
Therefore, LoRAP began stratigraphic investigations in two sites in the KSO area: in 2006 we opened two test trenches, which were followed by larger excavations in 2007 and 2008.
The first site (former Locus 1), locally called Khok Din (ca. 0.22 ha;) about 90 m south of KSO, is a low mound covered by wild vegetation. The small mound, unsuitable for agriculture, is made up of metallurgical residues: grit from treatment of the parent rocks mixed to crushed copper slag, bivalve terracotta casting moulds, and shards of technical and domestic ceramics. Such an assemblage was indeed alike the evidence the TAP had excavated in the industrial and residential site at Nil Kham Haeng in the Khao Wong Phrachan valley (Fig.s 5-6).