Roger is a manipulative individual who has no regard for the moral and ethical rules of society or the rights of others. it is most likely that he has:

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.

it depends on which society you are referring to. many civilization performed rituals so the gods would with their growing season but the most well known is that of the aztecs. they would make sacrifices, usually animals, but sometimes humans as well.