Which continent was the sight of the initial European imperialistic takeover of land and resources?

Africa and Asia were the first continents.

I would say that the South American continent and also the North American continent in Mesoamerica were the two sites where European colonialism mainly of the Spanish colonialists and also the Portuguese were responsible for the stealing of the natural resources and the subjugation of the native peoples like the Incas and Aztecs. While the initial conquests were brutal and barbaric, the good thing that the Spaniards did was inter-marry with the local native people and form a new society of largely mestizo or mixed people.