What factors contributed to European dominance in the nineteenth and twentieth centuries?

Three Words: nationalism, Imperialism, industrialism.

Europe was the first region to industrialize, meaning it had access to superior weaponry before anyone else. Because of the superior weapons and strong military that Europe had been developing, this allowed for Europe to imperialize other regions, Africa in particular, and allowed for a stronghold over natural resources and was able to spread its own ideologies to other countries (such as nationalism).