One of the first things Vladimir I did after he became the ruler of Kiev was to force the population to submit to his authoritarian rule.
make Orthodox Christianity the state religion.
isolate Kiev so that trade virtually stopped.
create a strong military for Kiev’s defense.

Make Orthodox Christianity the state religion

herodotus taught this. herodotus was an ancient greek historian who was born in halicarnassus in the persian empire. he is known for having written the book the histories, a detailed record of his "inquiry" on the origins of the greco-persian wars.