Ample evidence exists from ancient Indian texts, geomorphology and sedimentology that a mighty river that once originated in the Himalayas flowed in the North-west India during 7000-3000 BP and disappeared in the sands of the Rajasthan desert. Remote sensing combined with ground search identified part of the buried channel of the ancient river in the Jaisalmer region of Rajasthan. Isotope study showed that the fresh groundwater in that region was indeed ancient and slowly moving southwest and probably had headwater connection in the lower ranges of Himalayas, but not to any glacier. The isotope data (2H, 18O, 3H and 14C) compare well with the data in a similar study on another branch of the buried channel in the Cholistan part of the Thar Desert in Pakistan.