What do we call the transfer of goods, foods and ideas between the old world and the new world during the 1500's

imperial crisis leads to civil war.

roman forces withdraw from britain as goths attack rome.

odoacer topples romulus augustus

huns attack the empire and drive german peoples ahead of them.

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.