Treat them as Wild Warriors. They can be pushed. Try to use the enviroment to your advantage. Lower levels should try to face only one or two of them at a time. Three Bandits can knock out your shielding and damage reasonably well. When alone, Bandits are quite harmless, but with additional Bandits, Wild Warriors, or similar monsters they can kill a low level with ease. Practice caution and always carry some healing items.
People (often non-pvps) push AFK players to south of Thais where bandits can be roped. So be careful when going AFK if you need to do something else.