The decline of the Mediterranean sugar industry between the fourteenth and sixteenth centuries was paralleled by the concomitant rise of the Atlantic sugar industry, which, nonetheless, was not the principal cause of the waning of the trade in Mediterranean sugar. The temperate climate of the Mediterranean, as well as other impediments of geography such as a lack of rainfall, had always constituted obstacles to the successful development of large-scale production in Europe of what is essentially a tropical crop. But the key causes of this decline were European and Middle Eastern warfare, recurrent waves of the bubonic plague, the stagnation of technological development, and restrictive production and trade policies in certain important centers such as Egypt. In addition to these factors weakening the trade in Mediterranean sugar, the Portuguese, who had newly colonized the island of Madeira, began to cultivate sugar there in 1433 and by midcentury were exporting it back to Portugal. The production of sugarcane on the islands off the western coasts of Africa, colonized by the Portuguese and Spanish with the goal of exporting sugar to Europe, continued apace in the fifteenth and early sixteenth centuries, as Portuguese overseas expansion intensified. After Madeira, the Spanish introduced sugar production to the Canary Islands, and the Portuguese to the islands of São Tomé and Príncipe in the Gulf of Guinea, where a subtropical climate ideally suited to sugarcane production and an enslaved African workforce were, for the first time, associated with the plantation model that had been developed in the Mediterranean. See plantations, sugar and slavery. By the first decade of the sixteenth century, São Tomé sugar was being exported to Antwerp that, with Bruges and Lisbon, was the most vibrant hub of sugar refining and international sale in Western Europe, reflecting the dominance of the Spanish sugar trade in the sixteenth century, when the Netherlands were politically integrated into the sprawling Habsburg Spanish Empire. The southern provinces of the Netherlands, which contained Antwerp, remained under the control of Spain after confederation of the northern United Provinces in 1580. After this date Amsterdam, the new vibrant capital city of the United Provinces, began to compete with Antwerp in sugar refining and the sugar trade. See sugar refineries.