SEVERAL thousand years ago, the Indian subcontinent experienced significant upheavals. The northwest region trans-itioned into an arid zone, and the courses of rivers were greatly affected by erosion and tectonic events. One of the river courses disappeared, only for the British to discover it in the early 19th century through topographic exploration. Recently, geological and climatological experts have probed its evolution and disappearance, with satellite imagery tracing the river’s buried courses, and isotope analysis detecting ancient water still stored under the Thar desert. The Indus civilisation, which was the subcontinent’s first known urban settlement, did not benefit from the Indus River alone. Since Aurel Stein’s expedition in 1940, hundreds of Harappan sites have been identified in the now-dry Saraswati basin. The rich technological, artistic and cultural legacy of the Harappan civilisation laid the foundation for developing newer civilisations in the subcontinent.