Landscape in Rattanak Moudoul district, Battambang province. Since 1998, population migrations along the pioneer front resulted in large-scale forest conversions due to the rapid expansion of annual upland cash crops. Migrations have been also stimulated by flourishing international agribusinesses of cereals and tubers that facilitated farmers’ access to agricultural mechanization and agro-chemicals. Small to medium landholders were involved in this rapid conversion of vast degraded forest lands into cultivated land (from 120,000 ha in 2000 to 800,000 ha in 2012), leading to what can be considered as the first and biggest national social land concession. Intensive mono-cropping mainly for cassava and maize productions, based on tillage and herbicide use has resulted in significant soil erosion and land degradation. In a general context of labor scarcity, resources-rich farmers cope with the risks by shifting from annual crops to perennial crops. Poorest farmers who cannot afford such strategies may further fall into the poverty trap by selling out their land to the other farmer groups to become wage-earners in their former land. Ultimately, land concentration process may benefit the multinational agribusinesses that are engaged in large-scale land grabbing.