1640: The Iberian Union, which had united the monarchies of Spain and Portugal under a single crown for sixty years, officially came to an end.

1640: The Iberian Union, which had united the monarchies of Spain and Portugal under a single crown for sixty years, officially came to an end. This political shift had immediate consequences for the slave trade, as Portuguese ships could no longer legally deliver captives to Spanish colonial territories. The termination of the union forced the Spanish crown to seek alternative methods, such as the asiento contract system, to supply its colonies with labor. This transition marked the beginning of a more fragmented and competitive era of Atlantic maritime commerce.