Obsidian is a common lithic raw material extensively distributed in Sumatra's prehistoric sites. As a holohyaline volcanic glass it yields an almost perfect conchoidal fracture when knapped. For that reason, Sumatra's obsidian artifacts are usually associated with the expedient debitage method (i.e., razor-sharp flake production). However, its appearance in some specific sites has raised questions regarding raw-material procurement strategies. Obsidian tends to be widely distributed beyond its primary geological context as an allochthonous material. Simple observation of the cortical flakes demonstrates that the river must be responsible as a natural agent for transporting obsidian, but this is yet to be proven. Until recently, there was no robust evidence to connect obsidian artifacts in Sumatra with their source(s). But now using elemental determination via portable X-Ray Fluorescence (pXRF) we have been able to identify multiple obsidian sources, at least from southern Sumatra (Jambi and South Sumatra). Two out of three previously PIXE-PIGME and LA-ICP-MS identified groups by Ambrose et al. (2009) and Reepmayer et al. (2011) match pXRF determinations from two obsidian sourcing localities (OKU and Merangin-Kerinci). In this presentation we further enhance our knowledge of obsidian sources in Sumatra by adding two new sources from Sarolangun (Batang Asai 1 and Batang Asai 2). Principal component analysis (PCA) and independent sample t-test show these two sources are geochemically identical to obsidian artifacts from four nearby prehistoric sites in the Bukit Bulan Karstic Area. Although obsidian is widely distributed, our study reveals that its circulation seems limited to a specific area due to the availability of multiple sources. Here, we proposed that the study of obsidian distribution among the prehistoric sites in Sumatra could not rely only on geochemical study alone. A combined study of archaeology, geology, and physiography—especially surrounding a young volcanic deposit and the watershed—must be considered.