The Teaching Company's Medieval World lecture, conducted by Dorsey Armstrong is a great way to get into medieval history if your too busy. It has, like many TTC DVDs, a booklet with outlines and bibliographies which allows you to pursue particular aspects of interests.
I owe it to RPGs that got me into Medieval History. When I was in highschool, my brothers and I saved up to purchase Advanced Dungeon and Dragons Revisited, Combat and Tactics for P1200 around 1996. My high school term paper was about the hundred years war, which was highly unusual and difficult because we don't have accessible public libraries.
Interest in medieval socio-economics made me really appreciate the subject matter all the way to modern Philippine context. Analyzing how people tried to devise better ways of living with each other through game theory and evolution colored and enhanced my understanding. It helped me understand how interactive situations tend to have a flow or a manner of growing more complex.
As for games, understanding the simple allowed me to observe the key fundamental elements that result in the complex. So in the beginning of a games premise, as the story begins to move, I'm able to predict or anticipate to changes and apply skills and knowledge that make me more adaptable to facilitate the game.
Details, particularly historical details have a pronounced affect in how I observe and communicate. After learning so many things which I can't retain, I begin to see a patterns that allows me to organize and arrange the knowledge to more accommodating sizes. Simple ideas become extended to have more meanings and iterations, like what is a land holder, an aristocrat, the warrior class and the subtle differences that have a striking affect in the world around them.
Personal formulas or principles begin to form to accommodate how best to communicate certain ideas. The differences between various land holding people, peasants or freemen, serfs and slaves have profound causes and reason that can be found in the mundane.
An example, the rights to bear arms meant to a peasant. the duty to fight for your lord when summoned, also afforded these peasants the ability to demand rights in return. What it means to have one's destiny or happiness within their own grasp, as compared to the will of fate or one's lord. A peasant working a farm compared to a serf is much more productive not just because he doesnt lose 50% of his product, but because he directly benefits for his innovation.
There are many more profound ideas and ideals that make up the ordinary lives of people, that become extraordinary in the right conditions. These help in weaving detail and ideas to the shared story.
One other nice lesson I would like to point out is the mysteries found in history that allows us to play the role of "detective". Since many works are now available, as they came from pre-Information age, a layman-historian can now compare and refined by many other disciplines that are available at our finger tips. Physical Sciences and Game Theory, which allows me to form my own informed hypothesis is a challenging exercise that hones the GM craft regarding improvisation and escalating complexity.