Introduction

The social and economic structure of the Crown of Castile underwent significant changes in the transition from the Middle Ages to the modern era, partly due to the strong pace of urbanization, a process which had been going on for some time, as was also the case in the rest of Europe. The expansion of regional trade and the incorporation of Castilian products within Europe's trading networks were some of the most remarkable consequences of this process. These changes inevitably led to the emergence of collaborative efforts and collective actions that, as was usual in other territories, supplemented the individual activities of great merchants. By means of these occasional relationships, there came about an organized system based on regular commercial, social and political contacts through the participation of the most important merchant families, who generally shared the same neighbourhood. To live in the same city, in the same neighbourhood, even in the same street meant to share the daily life and favoured the creation of kinship relations or business in common. The example of Castilian merchants at the end of the fifteenth century and the beginning of the sixteenth century is very instructive as we try to understand how small local agents became large companies, corporations who had a strong familiar component and who were able to join the urban elite groups of the kingdom.