Asiento de negros

An asiento was similar to a patent in early modern England. A trade relationship was established whereby a set of traders was given a monopoly over that route and/or product. In this case, it refers specifically to a monopoly over the trade of slaves between Africa and the Americas. According to the Encyclopædia Britannica, this asiento existed between the early 16th and mid 18th century.

One of the results of the war of Spanish Succession was that England received the asiento as a compensation for the victory of the French candidate Philip V of Spain.The reason for such patents is that trade routes were not what we take for granted today. At the time, the development of ports on either side and facilities for the trade was very expensive to develop and more so to manage. The European governments found it easier and more lucrative to assign a monopoly (ostensibly protected by the armada) to a group of traders who would pay the government for the privilege and invest in the infrastructure to enable the trade. One must remember that these were pre-bureaucratic and fractured governments. Organization and leadership of distant activities was often placed in the hands of traders who would pay a flat fee. For the government, the sole purpose of these endeavours were money. The spread of Christianity should not be forgotten as a motivator, but this was always secondary to resources (gold, spices, etc.). There are many examples of Isabella referring to the Christianizing of the "heathens" but even she wouldn't have the resources for this if there weren't gold to pay for it. This is why Florida never gained significant development until much later. However it is a more modern concept that land had value above and beyond the resource extraction that could be gained by controlling it. So really, it is dangerous to look at the asiento or patent system as different from how we currently look at patents on drugs or technology. The government, in order to facilitate the development of such things, literally sells the right to them to gain rent from the exclusion of others.

Similar patents in the English system were the Virginia Company, the Levant Company, and the Merchant Adventurers' patent of trade with the United Provinces (pretty much concurrent with modern day Netherlands). A detailed and well written overview of the English system is given by John Brenner in "Merchants and Revolution".