Invaders with weaker immune systems tended not to write home boasting of their glorious deeds and inviting their friends and family to join in the enterprise. The European Colonization of Africa is a Good example, The trading posts on the coast predate Columbus, but the European Empires did not divide the land up until after 1850. The only Country today with a demographically significant White European population is South Africa, where according to Jared Diamond in Guns, Germ and Steel, the Disease pressure was significantly lower.
Was that because much of that nation is non-tropical?
Well, that’s interesting!