Globalization

Throughout history, what were causes for the advancement of globalization? In other words, what forces have driven globalization forward? Important: Be able to specify and explain these causes/forces. Note that �Aggressively Expanding Empires is considered one force/ cause (and that we look at a number of specific examples, such as The Roman Empire, etc.); �Trade is another force/cause (and we look at a number of examples, such as The Silk Road�).