The Nguom Rock Roof archaeological site in Kim Son hamlet, Than Sa commune (Vo Nhai), was ranked as a national relics in 1982. The Rock Roof is in the shape of a frog jaw, about 30m higher than the surface of the residential road and about 40m higher than the water level of Than Sa river.

The surface area of the rock roof with traces of the cultural layer is nearly 1,000 square meters. To date, Nguom Rock Roof has been excavated 5 times, in the years: 1981, 1982, 1985, 2017 and most recently in early 2024.