Certainly, some of them are mentioned in early Anglo-Saxon days among the qualifications for thegnhood, and when the lord possessed these things, he claimed a monopoly; his tenants were bound to grind their corn at his mill, and so forth. But there were things he did not care to do, and a villager here and there began to specialize in such trades as the blacksmith's, carpenter's, and mason's. This specialization involved co-operation and the expansion of household economy into village economy. Others must do the blacksmith's sowing and reaping, while he did the shoeing for the whole village. Thus village industries grew up, and in unprogressive countries, such as India, where, owing to distance and lack of communications, villages were isolated and self-sufficing, this village economy became stereotyped, and the village trades hereditary. But in western Europe, as order was slowly evolved after the chaos of the Dark Ages, communications and trade-routes were opened up; and whole villages began to specialize in certain industries, leaving other commodities to be produced by other communities. For the exchange of these commodities markets and fairs were established at various convenient centres; and this in turn led to the specialization of traders and merchants, who did not make, but only arranged for the barter of, manufactures. Through the development of local industries and markets, villages grew into towns, and towns expanded with the extent of the area they supplied. A town which supplied a nation with cutlery, for instance, was necessarily bigger than a town which only supplied a county. This expansion of markets meant that towns and cities were more and more specializing in some one or more industries, leaving the great majority of their needs to be supplied from elsewhere; and the whole process was based on the growing complexity of civilization, on the multiplying number of implements required to do the work of the world.