The present study investigates latero-frontal moraines to reconstruct the pattern of glacier advances and associated climate variability in the Suru valley, southwestern Zanskar Himalaya. Impressive sets of latero-frontal moraines and discontinuous morainic ridges (recessional) represent the records of the past glacier advance and retreat. The northerly trending latero-frontal moraines that descend down the tributary valleys and terminate at the trunk Suru valley are the geomorphic expression of one of the oldest preserved record of glacier advance and is named as Tongul glacial stage. Previous studies (based on $^{10}\rm{Be}$ and $^{14}\rm{C}$ ages) deBning the chronology of Tongul glacial stage are either limited in number ($^{14}\rm{C}$ ages) or have a large spread ($^{10}\rm{Be}$ ages) and hence demand further investigation. Optically stimulated luminescence (OSL) dating suggests that the Tongul glacial stage responded to the global last glacial maximum (gLGM) dated between $\sim$ 20 and 24 ka. We suggest that the Tongul glacial stage was driven by enhanced mid-latitude westerlies and reduced temperature (viz., continental cooling) during MIS 2 andfacilitated by corresponding long winters.