Spiti valley is located in the Trans-Himalayan terrain of India, from where non-geometric microliths have been discovered. While the Siwalik Hills have been subjected to extensive prehistoric surveys, this is the first evidence of lithic tools discovered in the Trans-Himalayan region of Himachal Pradesh, India. Due to its topographic and intense climatic features, the Trans- Himalayan region has generally been regarded as a barrier since prehistoric times. However, Dzamathang cannot be considered as an isolated site in the Trans- Himalayas. In fact, in the adjoining areas of Ladakh, Tibet and Nepal, similar lithics have been reported from several sites and assigned to the Middle and Upper Palaeolithic. The discovery of this site suggests that the Trans Himalayan zone may have acted as a possible route instead of a barrier during human migration. Large numbers of lithics have been recovered in the Dzamathang area of Spiti Valley. Based on the collection of the artefacts from the surface, this article tries to understand the geological and geographical setting of the area, particularly concerning prehistoric settlements in the Trans-Himalayas. This assemblage consists of assorted artefacts which includes a unifacial chopper, microlithic cores, flakes, blades, bladelets, burin, and a large amount of debitage fragments. The majority of artefacts are on quartzite or quartzarenite. Future surveys will be targeted at recovering primary context sites for excavations and absolute dating.