The Thar Desert, located in western South Asia, marks a major global biogeographic boundary and a major adaptive threshold for the eastward expansions of modern humans from Africa across Asia. Examining the framework of palaeoenvironmental change in this region, both in terms of the regional manifestation of global climate change and the physical geography of the landscape, is therefore important to understand how modern humans first engaged with this significant shift in ecology. Here, we present evidence for the oldest chronometrically dated evidence for fluvial activity within this region, located at the Nal Quarry site in the central Thar Desert. We use luminescence dating of alluvial facies to demonstrate phases of fluvial activity at the site at ∼172–174, 140–150, 79–95 and 26 thousand years ago. This result substantially extends existing evidence for fluvial activity within the Thar Desert, as well as overlapping with evidence from the southern and eastern Thar desert indicating increased fluvial activity during the Last Interglacial (Marine Isotope Stage 5), whereas the cessation of fluvial deposition at Nal Quarry is contemporaneous with the onset of activity within the Ghaggar-Hakkra channel in the northern and western Thar Desert. Critically, the phases of fluvial activity identified at Nal overlaps with substantial behavioural change across South Asia, as well as the wider expansion of modern humans across the continent. This research illuminates a dynamic fluvial landscape that existed in the late Middle Pleistocene and early Late Pleistocene at a key threshold for modern human dispersals.