What event led to the development of the two different european civilizations of the western roman empire and the eastern roman empire?

Invasions by Barbarian tribes.

During the 4th century, the Empire remained unified, with its headquarters in Constantinople. At the end of the century, Emperor Theodosius established, in 395, the definitive division: Roman Empire of the West, with capital in Rome, and Roman Empire of the East, also called Byzantine Empire, with capital in Constantinople.

the civil war started because of uncompromising differences between the free and slave states over the power of the national government to prohibit slavery in the territories that had not yet become states. when abraham lincoln won election in 1860 as the first republican president on a platform pledging to keep slavery out of the territories, seven slave states in the deep south seceded and formed a new nation, the confederate states of america. the incoming lincoln administration and most of the northern people refused to recognize the legitimacy of secession. they feared that it would discredit democracy and create a fatal precedent that would eventually fragment the no-longer united states into several small, squabbling countries.

i believe it caused a regional impact in societ