You had something like this during the European partitioning of Africa into colonial Empires. Africa was known as the “white man’s graveyard” due to various tropical diseases. In the end, for the most part, technology won, and Europe carved up Africa into various colonial Empires.

But it did take 400 years more technology than what Cortez had. The Zulu army was not a walk-over in the mid-19th C, although 50 years later (with gatling guns) it would have been.