From the book Rule:

They seemed a nomadic people, but they kept so wholly to themselves that I learned little. They would travel up and down the green ways where the setting was good. Instead they spent their time scouring this great unexplored land looking for something, things they didn’t fully understand but had become intricate to their way of life and societal structure. They sought them with a determination of the devoted. Ultimately they proved the truest of Rule’s inhabitants.