Daniel had been working as essentially a slave for Amalek. (His grandmother had sold him.) He eventually escapes, and when he does, he flees to the mountains. He is living there first, then, because it isn't the town of Galilee. A related reason is that the Romans are in the town; they don't really occupy the hill country (though they pass through it). Eventually, he lives there because that's where Rosh and his group live, and he's living with them to fight the Romans. That's where the rebels can find places to hide.
daniel is living on the mountain because after his hardships he undergoes through his early life he decides to run away from amalek,whom he works for. He escapes to a group of outlaws that live on a mountain. The leader of this group is named Rosh.