Industrialization allowed cheap production of household items using economies of scale, while rapid population growth created sustained demand for commodities. Nineteenth-century imperialism decisively shaped globalization in this period. After the First and Second Opium Wars and the completion of the British conquest of India, vast populations of these regions became ready consumers of European exports. During this period, areas of sub-Saharan Africa and the Pacific islands were incorporated into the world system. Meanwhile, the European conquest of new parts of the globe, notably sub-Saharan Africa, yielded valuable natural resources such as rubber, diamonds and coal and helped fuel trade and investment between the European imperial powers, their colonies, and the United States.