The Industrial Revolution and European imperialism were connected in several ways. One was that the Industrial Revolution created a demand for raw materials, including oil, rubber, timber, and iron, to name a few. Europeans sought cheap sources of these raw materials, and looked to colonies as a means of securing a steady supply. Another way was that the Industrial Revolution created what many saw at the time as a need for captive, secure markets. Many economists warned of the dangers of overproduction, which would be the inevitable result, they thought, of increasing efficiency in industry. Overproduction, it was argued, would lead to economic depression (as many thought it had during both the 1870s and 1890s). Securing markets for surplus European manufactured goods (China was especially inviting) was thus a major motive for imperialism. Finally, industrialization created the technology, especially weapons, that gave Europeans such a decided advantage over peoples around the world. In short, it made it possible for Europeans to colonize distant lands. It might also be argued that the Industrial Revolution gave some Europeans an ideological motive for imperialism. They interpreted their technological power as evidence of moral and even racial superiority, both of which justified conquest and colonization.