Answer:
Christianity
Explanation:
From a marginal religion to the dominance in Europe, Constantine took the first step in accepting Christians in 313, with the Edict of Milan, which instituted religious tolerance in the empire. In 380 AD, Theodosius I officialized this religion, and over time, the church became more powerful, controlling every aspect of the European society.
I don't know if you still need this but the answer is: To avoid an absolute, oppressive government.
The answer isthe mississippi river