I'm looking for techniques to write a fantasy story (A song of ice and fire style) but the problem is the duration of the story :
The first three years there are lot of plots, and betrayals.
After that a good lord rules the kingdom, in his reign nothing special happens, the plots against the king stop and everything is ok.
After his death the plots and betrayals resume
So the question is how can I skip the twenty years of his reign, mentioning just the important stuff without confusing readers?