The conversion of rangelands and barren lands into agricultural use destabilises fragile pastoralism. This study examines the drivers and impacts of this transformation on pastoralism in Tinghir province, Morocco, using geospatial analysis, semi-structured interviews with pastoralists, discussions with officials and document review. Land cover maps for 1984-2023 were created using Landsat and Sentinel-2A imagery. Maximum likelihood classification was applied using the NDVI index as a mask. Findings show a 5-248% increase in cropland, mainly from converting rangelands and barren lands. While the converted area is limited, it increasingly obstructs transhumance routes to winter pastures, as the new lands are perpendicular to these corridors. This has reduced grazing resources and sparked conflicts over passage rights and wells between pastoralists and farmers. Qualitative data indicate that rangeland conversion was initially driven by socio-economic, natural and technological factors, now reinforced by agricultural strategies promoting irrigated orchards and new land-tenure policies. These challenges highlight the need for a holistic management approach that balances pastoralism and agriculture, respects ecological limits and incorporates pastoralists' rights into land use planning. Recommendations include promoting crop-livestock synergies, protecting transhumance corridors and watering points, restoring rangelands, incentivising pastoralism and adopting an ecosystem-based approach to assess land conversion impacts.