Peaceful solution awards 180xp and the Patrol Leader and a single Centaur Warrior will move to the Tomb entrance.
In the second encounter at the Tomb Entrance you will meet Centaur Patrol Lieutenant, you can pass Intimidate DC 25 check for +360xp total and they will be gone or attack them.
Helping the Injured Dragon gives +360xp, killing him however gives 540xp.
Killing the Pale Yan gang gives +258xp total, but helping him gives +720xp. If the dragon is already dead/gone and you didn't attack the bandits then you get 540xp and they will go away.
The trick to cheese the experience and still get all their items is to team up with Pale Yan and then make him die with aoe spells and then finish off the dragon.
This spoils a hidden secret. Click here to toggle all spoilers on the page.
The first step is to find the Crystal Key in the ruins to the right of the Injured Dragon then insert it in the missing dais then light the crystals in the correct order (see picture).