What factors made travel into the interior of africa difficult for europeans? what invention of the industrial age changed that?

Between the 1870s and 1900, Africa faced European imperialist aggression, diplomatic pressures, military invasions, and eventual conquest and colonization. At the same time, African societies put up various forms of resistance against the attempt to colonize their countries and impose foreign domination.

Explanation:

answer; /// i do believe that its napolean's conquest of spain;