Legislation showed the double tendency of encouraging economic development and of checking it by laws looking to the temporary needs of the royal treasury. The _Partidas_ urged the cultivation of the soil, the building of bridges and repair of roads, the prevention of frauds in customs houses, and the exemption of certain imports from the payment of duty when they seemed likely to aid in material progress,--such as farming utensils when destined for use by the importer himself and not intended for resale. Commercial treaties with foreign countries began to be made in the fourteenth century, although often by merely a portion of the kingdom, particularly the north coast ports; thus there were treaties of 1351 and 1366 with England. On the other hand there were the royal monopolies, the _alcabala_, and the rigid maintenance of customs duties,--for the exemptions, after all, were few in number. Not only was there the obstacle of different state boundaries, but also there were the duties collected by many, if not most, of the towns. No distinction was made as to the source of goods, and those of Castile paid equally with foreign products. Another hindrance to economic advance was the well-intentioned, but mistaken, policy of excessive governmental regulation of the industries. Both the state and the guilds themselves made laws fixing wages, the hours of labor, prices, methods of contract, amount of interest, and even the way in which goods should be made. These regulations were not uniform for all Castile, but varied according to the special circumstances of the different regions. The municipalities also intervened to fix prices for goods of prime necessity or of general use. At times they granted an exclusive right of sale, or established municipal shops. [Sidenote: Progress in commerce.] To facilitate commerce fairs and general markets were greatly resorted to, being established by law, or, if already in existence, favored by grants of new privileges. The insecurity of the roads and the civil wars prevented the royal grants from having their full effect, and other circumstances, such as the popular attacks on Jewish districts, the variety and uncertainty of coins and of weights and measures, the debasement of the coinage by the kings, and the prevalence of counterfeiting (despite the penalty imposed,--burning to death), tended to interfere with commerce. Nevertheless, notable progress was made. Bills of exchange first appeared in this era. Foreign merchants visited Castile, and Castilians went abroad, especially to England and Flanders; there were Castilian consuls in Bruges. The Jews figured prominently in foreign trade, as money changers and makers of loans, while their international relations due to the solidarity of their race enabled them to act as bankers. [Sidenote: Public works.]