Some of this dramatic change, though on a smaller scale, occurred closer home in west Punjab. Here the British Indian government built a network of irrigation canals to transform semi-desert wastes into fertile agricultural lands that could grow wheat and cotton for export. The Canal Colonies, as the areas irrigated by the new canals were called, were settled by peasants from other parts of Punjab. Of course, food is merely an example. A similar story can be told for cotton, the cultivation of which expanded worldwide to feed British textile mills. Or rubber. Indeed, so rapidly did regional specialisation in the production of commodities develop, that between 1820 and 1914 world trade is estimated to have multiplied 25 to 40 times. Nearly 60 per cent of this trade comprised ‘primary products’–that is, agricultural products such as wheat and cotton, and minerals such as coal.