I do well enough against Khergits. I just have my men dismount and hold position in a valley while I shoot out the raider's horses with my crossbow or kill them with throwing axes to the head as they pass by. Once they're on foot, they're easy to kill off.
Also, Cleitan, how did you manage to lose all yours knights in one fight? You must have sent them charging into sea raiders waiting in a river or something.