What were the "ingredients" of the early medieval synthesis? how did they come to define the character of the west?

The ingredients of the early medieval synthesis are the following;

-          Population, agriculture and their cities

These three ingredients have come to define the character of the west as they were able to shape up the west in means of their life style and how the people engage with this life style in their every day activities that made the west to define its own character.

answer; ///the correct answer is,by introducing a merit system of nobility.