if you are on a horse, ride sideways when they are about to throw, and move in towards them when they are readying another throw. being on a horse is extremely dangerous against ranged, when you speed up to charge them you make ranged attack hit you really hard, so you need to put that speed away from them. you will notice if you ride away from looters throwing stones at you, even if you are naked like shinobis barbarian, they barely damage you 5 points, and should not damage you at all with armor on. this is why training yourself to have a good maneuver on a horse is important to stay alive on one. the damage from speed is also why ai never makes their cavalry charge until infantry is close enough to distract most targets. if you make cavalry charge in without infantry, they get shot down quick
big pro tip: do not ride pack horses! they cannot maneuver at all. it will get you killed fast against looters. you ride one when you start a new game, take that horse off, its bad. only good for carrying loot. buy a 10 lvl riding horse that cost between 150-300 and you are good to go
on the other hand if you are on foot, you have the best mobility, so you can 'dodge' the stones by moving sideways as they throw, and make them block each others view by circling around their position. it becomes easier as you level your athletics. but expect things to be a little difficult in the beginning when your character is untrained