A spatial analysis across Aravalli states shows profound consequences of reframing the definition of what counts as a hill and range in one of the world’s oldest mountain systems. In Rajasthan, over 70% of the current Aravalli extent would lose protection with the new definition, if passed. In Gujarat and Haryana, the figure rises to about 82%. In Delhi, the entire Aravalli extent falls below the elevation cut-off unless protected under separate instruments. Additionally, nearly 41.8% of the natural vegetation in Rajasthan’s Aravallis, including two-thirds of the state’s savannah grasslands, all of its sand dunes and 18.35 sq. km. of its forests are at risk. The views, findings and analysis are those of the authors. The findings are not independently verified by Mongabay-India.