For the constant supply of natural resources and other essential goods colonies used to annex other countries and the custom was followed by French also. The French in order to expand its territories began building canals and draining lands in the Mekong delta to increase cultivation. The vast system of irrigation works—canals and earthworks—built with forced labour, increased the production of rice and allowed the export of rice to the international market. The area under rice cultivation went up from 274,000 hectares in 1873 to 1.1 million hectares in 1900 and 2.2 million in 1930. By 1931, Vietnam became the third largest exporter of rice in the world.
