Between 1935 and 1960 a peculiar patterning of forced labour developed on Mozambique's lower Zambezi. By the beginning of the Salazar era a particular style of history had been imprinted upon Mozambique. Large scale recruiting of labour for the mines and farms of southern Africa coupled with mass migrations of Mozambique's people to escape the oppressions of Portuguese administration resulted in a severe labour shortage which companies operating in the colony had to face. Exacerbating this problem was the Portuguese decision in the mid-1930s to compel the colonies to produce enough cotton for the demands of the empire. To protect its position vis-à-vis already scarce male labour, the Sena Sugar Estates Ltd., Mozambique's largest employer of labour, formulated a system by which only female labour would cultivate cotton, leaving the men free to work in the company's sugar fields. This system, which was adopted in the 1940s by other employers of labour, led to severe oppression of the local people, notably the women, who were caught between the conflicting demands of interests more powerful than themselves. Only in the late 1950s and early 1960s did the pressures of the forced cultivation system end.